Articulatable members having constrained motion and related devices and methods

ABSTRACT

An articulatable member includes a distal end, a proximal end, an actuation member, and a constraint member. The actuation member extends from the proximal end to the distal end. The actuation member transmits force to bend the articulatable member from a neutral position. The constraint member extends from the proximal end to the distal end. The constraint member may have opposite ends that are fixed to the distal end and the proximal end. In one embodiment, the constraint member follows a helical path along at least a portion of the articulatable member from the proximal end to the distal end. In another embodiment, the actuation member follows a helical path along at least a portion of the articulatable member.

RELATED APPLICATIONS

This application is the U.S. national phase of international applicationno. PCT/US2015/015849 (filed Feb. 13, 2015), which designated the UnitedStates and claimed right of priority to U.S. provisional patentapplication No. 61/943,106 (filed Feb. 21, 2014), both of which areincorporated herein by reference.

TECHNICAL FIELD

Aspects of the present disclosure relate to articulatable members thatexhibit constrained motion. More particularly, aspects of the presentdisclosure relate to surgical instruments, and related systems andmethods, utilizing such articulatable members.

BACKGROUND

Remotely controlled surgical instruments, which can include teleoperatedsurgical instruments as well as manually operated (e.g., laparoscopic,thorascopic) surgical instruments, are often used in minimally invasivemedical procedures. During medical procedures, an instrument may bearticulated to position a portion of the instrument in a desiredlocation. Positioning of the instrument in a desired location ororientation can be achieved by constraining the motion of one or morejoints of the instrument. However, mechanisms to constrain the motion ofone or more joints of an instrument can increase the mechanicalcomplexity and operation of an instrument, and increase the difficultyof manufacturing an instrument.

The overall size of minimally invasive surgical instruments may poseconstraints on the design of surgical instruments. In variousapplications, it is desirable for the overall size, including the outerlateral dimensions (e.g., diameter), of such instruments to berelatively small to fit within narrow lumens and other passages. In somecases, therefore, it is desirable to select the number and placement offorce transmission elements so as to reduce the overall size of theinstruments. For example, the number and placement of force transmissionelements that interconnect a series of articulably coupled links toprovide actuation forces to control bending of the links may be suchthat the one or more force transmission elements pass through one ormore links without directly attaching and terminating at such links. Forexample, the bending and steering of a plurality of joints (or linkpairs) in a series may be actuated through a single force transmissionelement (or single set of force transmission elements in the case ofmultiple bend directions and or degrees of freedom (DOFs)) without eachjoint or link pair being capable of individual direct bending byactuation of a force transmission element directly attached to such alink pair. Such a configuration is sometimes referred to as“underconstrained.” In other words, the steering and bending of multiplelink pairs is actuated by a single force transmission element or singleset of force transmission elements that is attached to and terminates ata link of one of the link pairs. Such “underconstrained” structures,however, can pose challenges in attempting to controllably steer andbend the structure, thereby potentially resulting in unpredictableand/or uncontrollable movement (articulation) of the links.

Control systems and other mechanisms have been proposed to assist inconstraining the movement of otherwise underconstrained jointed linkstructures. However, a need exists to provide alternate designs forarticulatable members that achieve constrained motion so as to be ableto accurately control movement and positioning of the articulatablemember.

SUMMARY

Exemplary embodiments of the present disclosure may solve one or more ofthe above-mentioned problems and/or may demonstrate one or more of theabove-mentioned desirable features. Other features and/or advantages maybecome apparent from the description that follows.

In accordance with at least one exemplary embodiment, an articulatablemember comprises a distal end, a proximal end, an actuation member, anda constraint member. The actuation member may extend from the proximalend to the distal end. The actuation member may transmit force to bendthe articulatable member from a neutral position. The constraint membermay extend from the proximal end to the distal end. The constraintmember may have opposite ends that are fixed to the distal end and theproximal end, respectively. Further, the constraint member may follow ahelical path along at least a portion of the articulatable member fromthe proximal end to the distal end.

In accordance with another exemplary embodiment, an articulatable membermay comprise a proximal end, a distal end, an actuation member, and aconstraint member. The actuation member may extend from the proximal endto the distal end. The actuation member may be configured to transmitforce to bend the articulatable member from a neutral position. Theconstraint member may extend from the proximal end to the distal end.The constraint member may have opposite ends that are fixed to thedistal end and the proximal end, respectively. Further, the actuationmember may follow a helical path along at least a portion of thearticulatable member between the proximal end and the distal end of thearticulatable member.

In accordance with another exemplary embodiment, a surgical instrumentcomprises a shaft, a force transmission mechanism connected to aproximal end of the shaft, a parallel motion mechanism connected to adistal end of the shaft, a wrist, an actuation member, and a constraintmember. The wrist may comprise a plurality of links and be coupled to adistal end of the parallel motion mechanism. The actuation member maytransmit force from the force transmission mechanism to bend thearticulatable member from a neutral position or bend the wrist from aneutral position. The constraint member may extend through at least thewrist. The constraint member may passively constrain motion of the wristmechanism. Opposite ends of the constraint member may be respectivelyfixed to a proximal end and a distal end of the wrist.

Additional objects, features, and/or advantages will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the present disclosureand/or claims. At least some of these objects and advantages may berealized and attained by the elements and combinations particularlypointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the claims; rather the claims should beentitled to their full breadth of scope, including equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be understood from the following detaileddescription, either alone or together with the accompanying drawings.The drawings are included to provide a further understanding of thepresent disclosure, and are incorporated in and constitute a part ofthis specification. The drawings illustrate one or more exemplaryembodiments of the present teachings and together with the descriptionserve to explain certain principles and operation.

FIG. 1A shows a teleoperated surgical system, according to an exemplaryembodiment.

FIG. 1B shows a portion of a manipulator arm of a patient side cart,according to an exemplary embodiment.

FIG. 2 is a top view of an exemplary embodiment of a surgical instrumentincluding a force transmission mechanism.

FIG. 3 is a partial view of a distal portion of a surgical instrumentincluding a jointed link structure, according to an exemplaryembodiment.

FIG. 4 is a partial top view of a shaft portion and force transmissionmechanism of an instrument, according to an exemplary embodiment.

FIG. 5 is the partial view of FIG. 3 with disks removed to revealinternal components.

FIG. 6 is a perspective view of an actuation member in a helical shapeand projection in a plane of the angular extent of the helical shape,according to an exemplary embodiment.

FIGS. 7A and 7B are a side view of an exemplary embodiment of a jointedlink structure and cross-sectional views of disks of the jointed linkstructure to illustrate a helical path of a constraint tendon.

FIG. 8A is atop perspective view of a disk of a jointed link structure,according to an exemplary embodiment.

FIG. 8B is a top perspective view of a disk of a jointed link structure,according to an exemplary embodiment.

FIG. 9 is a partial view of a distal portion of a surgical instrumentincluding a jointed link structure, according to an exemplaryembodiment.

FIG. 10 is a cross-sectional view along line 10-10 in FIG. 9.

FIG. 11 is a side view of a wrist including a braided structure,according to an exemplary embodiment.

FIG. 12 is an enlarged view of area FIG. 12 in FIG. 11.

FIG. 13 is a view along line 13-13 in FIG. 11.

FIG. 14 is a side view of a distal portion of a surgical instrumentincluding a jointed link structure with a braided structure, accordingto an exemplary embodiment.

FIG. 15 is a side view of a jointed link structure including a braidedstructure, according to an exemplary embodiment.

FIG. 16 is a partial perspective view of a distal portion of a surgicalinstrument including a parallel motion mechanism, according to anexemplary embodiment.

FIG. 17 is a partial perspective view of the distal portion of thesurgical instrument of FIG. 16 with the parallel motion mechanismactuated into a deflected configuration, according to an exemplaryembodiment.

FIG. 18 shows the view of the distal portion of the surgical instrumentof FIG. 16 with external surfaces removed to facilitate viewing ofvarious internal components.

FIG. 19 is a schematic perspective view of a central tube and actuationmembers extending through a parallel motion mechanism, according to anexemplary embodiment.

FIG. 20 is an end view of a disk of a parallel motion mechanism,according to an exemplary embodiment.

FIG. 21 is a partial perspective view of a distal portion of a surgicalinstrument including a wrist and a parallel motion mechanism with sharedconstraint mechanism(s), according to an exemplary embodiment.

DETAILED DESCRIPTION

This description and the accompanying drawings that illustrate exemplaryembodiments should not be taken as limiting. Various mechanical,compositional, structural, electrical, and operational changes may bemade without departing from the scope of this description and theclaims, including equivalents. In some instances, well-known structuresand techniques have not been shown or described in detail so as not toobscure the disclosure. Like numbers in two or more figures representthe same or similar elements. Furthermore, elements and their associatedfeatures that are described in detail with reference to one embodimentmay, whenever practical, be included in other embodiments in which theyare not specifically shown or described. For example, if an element isdescribed in detail with reference to one embodiment and is notdescribed with reference to a second embodiment, the element maynevertheless be claimed as included in the second embodiment.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages, orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about,” to the extent they are not already so modified.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired propertiessought to be obtained. At the very least, and not as an attempt to limitthe application of the doctrine of equivalents to the scope of theclaims, each numerical parameter should at least be construed in lightof the number of reported significant digits and by applying ordinaryrounding techniques.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” and any singular use of anyword, include plural referents unless expressly and unequivocallylimited to one referent. As used herein, the term “include” and itsgrammatical variants are intended to be non-limiting, such thatrecitation of items in a list is not to the exclusion of other likeitems that can be substituted or added to the listed items.

Further, this description's terminology is not intended to limit thedisclosure or claims. For example, spatially relative terms—such as“beneath”, “below”, “lower”, “above”, “upper”, “proximal”, “distal”, andthe like—may be used to describe one element's or feature's relationshipto another element or feature as illustrated in the orientation of thefigures. These spatially relative terms are intended to encompassdifferent positions (i.e., locations) and orientations (i.e., rotationalplacements) of a device in use or operation in addition to the positionand orientation shown in the figures. For example, if a device in thefigures is inverted, elements described as “below” or “beneath” otherelements or features would then be “above” or “over” the other elementsor features. Thus, the exemplary term “below” can encompass bothpositions and orientations of above and below. A device may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein interpreted accordingly. The relativeproximal and distal directions of surgical instruments are labeled inthe figures.

In various instruments with articulatable members, such as jointed linkstructures, movement of the articulatable member is constrained byactively controlling the movement of the components of the articulatablemember (e.g., disks). Actuation members, such as drive tendons or driverods, used to articulate the articulatable member may also be used toactively constrain the movement of the articulatable member. Forinstance, the actuation members may be coupled to a force transmissionmechanism, such as a gimbal cable actuator described in U.S. Pat. No.6,817,974, and coupled to disks of a jointed link structure so thatforce transmitted to the actuation members via the force transmissionmechanism may be used to move the disks and articulate the jointed linkstructure. This configuration may also be used to actively constrain themovement of the disks, such as by transmitting force from the forcetransmission mechanism to the actuation members to hold the disks inplace.

In some cases, instruments that actively constrain movement viaactuation members utilize a relatively large number of actuation membersto accurately control the movement of the articulatable member when thearticulatable member is articulated or its movement is constrained. Forexample, a wrist may include additional joints to increase the range ofmotion of the wrist. However, this may result in additional actuationmembers to actuate and/or constrain the additional joints, therebyincreasing the complexity and cost of the wrist, particularly when thejoints are actively constrained. Moreover, particularly for instrumentshaving a smaller diameter, it is generally desirable to use feweractuation members so as to conserve space within the instrument. Asidefrom their number, the nature of actively controlled constraint members(e.g., actuation members that are used to actively constrain themovement of an articulatable member using forces applied to theactuation members) can increase the complexity of a wrist due to themechanisms used to apply a force to the actuation members. Therefore, itmay be desirable to provide constraint members that are not activelyconstrained.

Various exemplary embodiments of the present disclosure contemplatearticulatable members in which the movement of the articulatable membersis passively constrained. In other words, movement of the articulatablemember is constrained without the use of an actuator, such as a forcetransmission mechanism and control algorithms controlling the same. Forexample, in various exemplary embodiments, the movement of disks of ajointed link structure is passively constrained by constraint membersthat are not actuatable by an external drive or transmission mechanism,but rather are reactive to motion (articulation) of the jointed linkstructure itself. According to an exemplary embodiment, the constraintmembers may be fixed at opposite ends of the jointed link structure. Asa result, the constraint members need not utilize force transmissionmechanisms to actively constrain movement of the articulatable member,which permits the use of fewer actuation members and potentially lesscomplex force transmission mechanisms. Further, ends of the constraintmembers may be secured at the opposite ends of the articulatable member.Thus, the constraint members need not extend to a proximal end of aninstrument where actuators, such as a force transmission mechanism, arelocated, thereby conserving space along an instrument shaft proximal tothe articulatable member. Further, by not extending constraint membersthrough the lumen (e.g., shaft) of an instrument to the proximal end ofthe instrument, the internal space of the lumen may be easier to cleanbecause there are fewer objects within the lumen.

In accordance with various exemplary embodiments, the present disclosurecontemplates articulatable members for instruments that includemechanisms to constrain the motion of the articulatable members. Theconstraint mechanisms may be secured at opposite ends of thearticulatable member, which may be a wrist, a parallel motion mechanism,or other articulatable member used in an instrument. In variousexemplary embodiments the articulatable members are jointed linkstructures. In one exemplary embodiment of a wrist of an instrument, theconstraint mechanisms extend along a helical path along at least aportion of the length of the wrist. The wrist may further includeactuation members, such as drive tendons, that extend substantiallystraight through the wrist. The wrist may include a series of connecteddisks that pivot about rotational axes that alternate in differentdirections (e.g., orthogonal) or that pivot about at least twoconsecutive rotational axes extending in substantially the samedirection. A constraint mechanism is not limited to a tendon or a rodbut instead may be, for example a braided structure, which may be usedto provide the structure of an articulatable member, such as byreplacing the disks of a jointed link structure. Alternatively, abraided structure can be used to constrain the motion of disks of ajointed link structure. In a parallel motion mechanism, the constraintmechanisms may extend substantially straight through the parallel motionmechanism, while drive tendons for the parallel motion mechanism extendalong a helical path as they extend through at least a portion of thelength of the parallel motion mechanism. According to an exemplaryembodiment, when an instrument includes both a wrist and a parallelmotion mechanism, a constraint mechanism can be used to constrain themotion of at least the wrist or both the wrist and the parallel motionmechanism. In another example, separate constraint mechanisms can beused to respectively constrain the motion of the wrist and the parallelmotion mechanism.

Referring now to FIG. 1A, an exemplary embodiment of a teleoperatedsurgical system 100 is shown, which includes a patient side cart 110, asurgeon console 120 for receiving input from a user to controlinstruments of patient side cart 110, and an auxiliary control/visioncart 130. System 100, which may, for example, be a da Vinci® SurgicalSystem, da Vinci® Si (model no. IS3000), Single Site da Vinci® SurgicalSystem, or a da Vinci® Xi Surgical System available from IntuitiveSurgical, Inc. However, various other teleoperated surgical systemconfigurations may be used with the exemplary embodiments describedherein. Referring now to the schematic illustration of FIG. 1B, aportion of an exemplary embodiment of a manipulator arm 140 of a patientside cart with two surgical instruments 141, 142 in an installedposition is shown. The schematic illustration of FIG. 1B depicts onlytwo surgical instruments for simplicity, but more than two surgicalinstruments may be received in an installed position at a patient sidecart as those having ordinary skill in the art are familiar with. Eachsurgical instrument 141, 142 includes an instrument shaft 150, 151 thatat a distal end has a moveable end effector (discussed below in regardto FIG. 2) or a camera or other sensing device, and may or may notinclude a wrist mechanism (discussed below in regard to FIG. 2) tocontrol the movement of the distal end.

In the exemplary embodiment of FIG. 1B, the distal end portions of thesurgical instruments 141, 142 are received through a single portstructure 152 to be introduced into the patient. Other configurations ofpatient side carts that can be used in conjunction with the presentdisclosure can use several individual manipulator arms. In addition,individual manipulator arms may include a single instrument or aplurality of instrument. Further, an instrument may be a surgicalinstrument with an end effector or may be a camera instrument or othersensing instrument utilized during a surgical procedure to provideinformation, (e.g., visualization, electrophysiological activity,pressure, fluid flow, and/or other sensed data) of a remote surgicalsite.

Force transmission mechanisms 147, 148 are disposed at a proximal end ofeach shaft 150, 151 and connect through a sterile adaptor 145, 146 withactuation interface assemblies 143, 144. Actuation interface assemblies143, 144 contain a variety of mechanisms (discussed further below withregard to the exemplary embodiment of FIG. 2) that are controlled by acontroller (e.g., at a control cart of a surgical system) to respond toinput commands at a surgeon side console of a surgical system totransmit forces to the force transmission mechanisms 147, 148 to actuateinstruments 141, 142.

The diameter or diameters of an instrument shaft, wrist, and endeffector are generally selected according to the size of the cannulawith which the instrument will be used and depending on the surgicalprocedures being performed. In various exemplary embodiments, a shaftand/or wrist about 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm in diameter,for example, to be inserted in some existing cannula systems; however,larger instrument sizes are also considered as within the scope of thepresent disclosure. According to an exemplary embodiment, depending onthe type of surgical instrument, one or more of surgical instruments141, 142 may be in communication with a flux source 160 via a fluxtransmission conduit 132. For example, if a surgical instrument 141 isan electrosurgical instrument, flux transmission conduit 132 is anelectrical energy transmission cable and flux source 160 is anelectrical energy generator.

Turning to FIG. 2, a bottom schematic view of a surgical instrument 240is shown, according to an exemplary embodiment. Surgical instrument 240may include a force transmission mechanism 250, a shaft 260 connected toforce transmission mechanism 250 at a proximal end 263 of shaft 260, andan end effector 280 connected to a distal end 265 of shaft 260.According to an exemplary embodiment, end effector 280 may be coupled tothe distal end 265 of shaft 260 via a wrist 270, as shown in FIG. 2.Wrist 270 may be actuated in one or more degrees of freedom (DOF's)(e.g., pitch, yaw, roll) to position end effector 280 at a desiredlocation.

Instrument 240 may include other joints, such as a parallel motionmechanism (not shown) positioned between distal end 265 of shaft 260 andwrist 270, according to an exemplary embodiment. For further detailsregarding exemplary parallel motion mechanisms and their functionsreference is made to U.S. Pat. No. 7,942,868, issued May 17, 2011, andU.S. Pub. No. US 2008/0065105, published Mar. 13, 2008, both of whichare incorporated by reference herein in their entireties.

Surgical instrument 240 may include one or more actuation members totranslate force between force transmission mechanism 250 and endeffector 280 and between force transmission mechanism 250 and wrist 270and/or a parallel motion mechanism (not shown). For instance, one ormore actuation member(s) 290 may connect force transmission mechanism250 to end effector 280 to provide actuation forces to end effector 280.The actuation members may extend along an interior of shaft 260. Byutilizing actuation member(s) 290, force transmission mechanism 250 mayactuate end effector 280 to, for example, to control a jaw of endeffector 280 (or other moveable part) and/or control wrist 270 ofinstrument 240. Actuation member(s) 290 may be tension members, such as,for example, cables, wires, or the like, and may actuate the surgicalinstrument in a pull-pull manner. In another exemplary embodiment, theactuation member(s) 290 can be a compression member, such as, forexample, a push rod, or the like, and operate in a push-pull manner, asdescribed in U.S. Pat. No. 8,545,515, issued on Oct. 1, 2013, which ishereby incorporated by reference in its entirety.

Force transmission mechanism 250 may include one or more components toengage with a patient side cart of a teleoperated surgical system totranslate a force provided by patient side cart to surgical instrument240. According to an exemplary embodiment, force transmission mechanism250 includes one or more driver disks 252, 254 that engage with apatient side manipulator of patient side cart, as described in U.S. Pat.No. 8,545,515. Thus, driver disks 252, 254 utilize actuation forces froma teleoperated (robotic) manipulator to actuate various DOFs ofinstrument 240, including, but not limited to, for example, roll, pitch,yaw, and/or various end effector movements (e.g., open, close,translate). Force transmission mechanism 250 is not limited to twodriver disks 252, 254 and may include fewer or greater numbers of driverdisks. For instance, force transmission mechanism 250 may include anumber of driver disks corresponding to the number of DOFs of instrument240, with some disks, or combination of disks, potentially controllingmultiple instrument DOFs. In addition, although driver disks 252, 254are depicted as being substantially parallel to the plane of the page ofFIG. 2, which results in the rotational axes (not shown) of driver disks252, 254 extending substantially perpendicular to the plane of the pageof FIG. 4, while shaft 260 extends substantially parallel to the planeof the page of FIG. 4, the embodiments described herein may use forcetransmission mechanisms that include driver disks arranged in otherconfigurations, such as, for example, driver disks having rotationalaxes extending substantially parallel to shaft 260.

The diameter or diameters of shaft 260, wrist 270, and end effector 280for surgical instrument 240, as well as the diameter of a camerainstrument, are generally selected according to the size of the cannulawith which the instrument will be used. In another exemplary embodiment,a diameter of camera instrument and a diameter of wrist 270 and mainshaft 260 may range from about 3 mm to about 10 mm. In another exemplaryembodiment, a diameter of camera instrument and a diameter of wrist 270and main shaft 260 may range from about 5 mm to about 8 mm. For example,the diameter may be about 4 mm, about 5 mm, about 6 mm, about 7 mm, orabout 8 mm, for example so as to be sized to be inserted within someexisting cannula systems. Further, although instruments may havecircular cross-sections, instruments with non-circular cross-sectionsalso are contemplated. For instance, a camera instrument may have anoval-shaped cross-section, such as a cross-section with a major axishaving a length of, for example, about 13 mm to about 17 mm, and a minoraxis having a length of, for example, about 8 mm to about 10 mm.

Systems and techniques for constraining the movement (bending) ofarticulatable members, such as wrists, may permit precise control of themovement of an articulatable member by minimizing undesired movement ofcomponents of the articulatable member. For instance, a constraintmechanism can minimize movement of disks in unintended directions, whichmay lead to slipping or dislocation of a disk relative to other disks ina jointed link structure or to an S-shape configuration when an arcshape with a single inflection may be desired.

As discussed above, motion of an articulatable member, such as a wrist,may be actively constrained by connecting a set of actuation elements(e.g., tendons) to one or more force transmission mechanisms, such asforce transmission mechanism 250. Various mechanisms in a transmissionmechanism of the instrument may be utilized to provide control over theactuation elements and thereby serve to constrain motion of jointed linkstructures or other articulatable member.

A constraint configuration utilizing sets of cables that terminate ateach of a series of disks to actively control motion of disk and thatextend to a force transmission mechanism at a proximal end of aninstrument can increase the mechanical complexity of an instrument andtake up valuable space in smaller instruments that may be used for othercomponents.

In view of these considerations, various exemplary embodiments of thepresent disclosure contemplate articulatable members that exhibitconstrained motion so that articulated movement of the articulatablemember is conducted in a relatively repeatable, precise, and smoothmanner to position the articulatable members in a desired andpredictable configuration. Further, an instrument including anarticulatable member in accordance with exemplary embodiments of thepresent disclosure may have a mechanically less complex forcetransmission mechanism despite a relatively small overall diameter ofthe instrument, may be relatively easy to operate, and may be costefficient to manufacture.

According to an exemplary embodiment, an articulatable member havingconstrained motion is a jointed link structure used as a wrist in asurgical instrument. Turning to FIG. 3, a distal portion 300 of aninstrument shaft is shown. By way of non-limiting example, the surgicalinstrument may be a camera instrument or a surgical instrument with anend effector supported by a wrist according to the exemplary embodimentsof FIG. 2. For instance, an end effector or camera device (not shown)may be connected to a distal end 302 of surgical instrument distalportion 300, which may be, for example, a collar. As shown in FIG. 3,distal portion 300 may include a wrist 310 connected to a portion 316 ofan instrument proximal to wrist 310. The portion 316 may be, forexample, a distal end of an instrument shaft, according to the exemplaryembodiment of FIG. 2, or may be a distal end of a parallel motionmechanism, as will be discussed below. Wrist 310 is a jointed linkstructure that includes a plurality of disks connected at joints betweenthe disks to provide motion to wrist 310 in arbitrary pitch and/or yawdirections. For instance, wrist 310 may include disks 311-315, althoughother numbers of disks may be utilized in a wrist, such as seven disks(such as in a wrist mechanism with six joints), eight disks (such as ina wrist with seven joints), or even larger numbers of disks. Althoughthe exemplary embodiments described herein are described as includingdisks, this is only one possible non-limiting configuration. Forinstance, links may be used instead of disks for the exemplaryembodiments described herein. According to an exemplary embodiment,disks 311-315 may include mechanical stops (not shown) to limit themotion of wrist 310, such as in pitch and/or yaw directions.

As depicted in FIG. 3, wrist 310 further includes a joint 322 providingan axis of rotation 350 between the pair of disks 311 and 312; a joint324 providing an axis of rotation 352 between the pair of disks 312 and313; a joint 326 providing an axis of rotation 354 between the pair ofdisks 313 and 314; and a joint 328 providing an axis of rotation 356between the pair of disks 314 and 315. The axes 350 and 354 extend insubstantially the same direction as each other, and axis 352 and 356extend in substantially the same direction as each other and in adirection substantially orthogonal to axes 350 and 354. Thus, axes 350,352, 354, 356 are arranged to provide arbitrary pitch and yawdirectional movement of the joints 322, 324, 326, and 328, with axes350, 352, 354, 356 alternating in differing directions, as shown in FIG.3. Although joints 322, 324, 326, 328 are depicted in the exemplaryembodiment of FIG. 3 as each having a single axis (axes 350, 352, 354,356 for each of joints 322, 324, 326, 328, respectively) joints 322,324, 326, 328 may instead include other numbers of axes. For example,joints 322, 324, 326, 328 may articulate according to the exemplaryembodiments of U.S. Pat. No. 8,911,428, published Dec. 16, 2014, whichis hereby incorporated by reference in its entirety, including theexemplary embodiment of FIG. 25 of U.S. Pat. No. 8,911,428.

As shown in the exemplary embodiment of FIG. 3, one or more actuationelements 320 extend through wrist 310. The actuation elements 320 may betendons used, for example, to actuate wrist 310, such as by fixingdistal ends of actuation elements 320 to a distal end 302 of instrumentshaft portion 300 or to disk 311 of wrist 310. In another example, oneor more actuation elements 320 may be used to actuate other componentsof an instrument, such as an end effector of a surgical instrument, suchas according to the actuation member 290 and end effector 280 of theexemplary embodiment of FIG. 2. Actuation elements 320 may extendsubstantially straight as actuation elements 320 through wrist 310,according to an exemplary embodiment, and as illustrated in FIG. 3.

According to an exemplary embodiment, actuation elements 320 may bearranged in pairs that extend through wrist 310, a shaft of aninstrument, and to a force transmission mechanism. The forcetransmission mechanism may include various types of mechanisms toactuate the actuation elements, such as, for example, capstans, gears,levers, gimbals, rack and pinion devices, pulleys, and other devicesthose having ordinary skill in the art are familiar with. For instance,four actuation elements 320 arranged in two pairs may extend throughwrist 310, although other numbers of actuation elements 320 and pairs ofactuation elements 320 may be utilized. A pair of actuation elements 320may be connected to a capstan to actuate actuation elements 320, such asin the form of a pull/pull drive mechanism or a push/pull drivemechanism, as described in U.S. Pat. No. 8,545,515. The capstan may beconnected, according to an exemplary embodiment, to one of the interfacedisks 252, 254 of the force transmission mechanism 250 of the exemplaryembodiment of FIG. 2, which transmit forces received from a patient sidemanipulator of a patient side cart 110 of the exemplary embodiment ofFIG. 1A, causing capstan to rotate and actuate actuation elements 320.Other force transmission mechanisms also may be used as those havingordinary skill in the art are familiar with, with the capstans being anon-limiting and exemplary configuration.

As shown in the exemplary embodiment of FIG. 4, actuation elements 364may extend through a shaft 362 of an instrument to the forcetransmission mechanism 360, such as when actuation elements 364 arepull/pull actuation members. In another exemplary embodiment, actuationelements 364 may be push/pull actuation members and capstans 366 may bereplaced with gears to drive actuation elements 364. Force transmissionmechanism 360 may be configured according to the exemplary embodiment ofFIG. 2. For instance, force transmission mechanism 360 may includeinterface driver disks to actuate capstans 366, similar to interfacedriver disks 182, 184 of the exemplary embodiment of FIG. 2.

Wrist 310 may include structures to passively constrain the motion ofwrist 310. According to an exemplary embodiment, wrist 310 may includeone or more constraint tendon(s) that extend through wrist 310. Toconstrain the motion of wrist 310, constraint tendon(s) may be fixed tothe distal and proximal ends of wrist 310. According to an exemplaryembodiment, passive constraint tendon(s) may be fixed to ends of anarticulatable portion of wrist 310, such as, for example, thearticulatable portion provided by disks 311-315. Thus, as will bediscussed below, passive constraint tendon(s) may be fixed to, forexample, disks 311 and 315 themselves or to positions proximate to disks311 and 315. When wrist 310 is articulated to bend a desired direction,the constraint tendon(s) will be bent with wrist 310. Because constrainttendon(s) are fixed to the distal and proximal ends of wrist 310,constraint tendon(s) have a fixed length relative to the wrist 310,causing the constraint tendon(s) to passively apply a force to disks311-315. Thus, if one of disks 311-315 begins to translate in a radialdirection relative to the other disks, constraint tendons will act uponthe translating disk so as to tend to resist the translation movementand keep the disk aligned along the longitudinal axis of the wrist. Forinstance, if disk 313 experiences a force that acts to translate disk313 radially along direction 358 relative to disks 312 and 314,constraint tendons in contact with disk 313, such as by passing throughapertures in disk 313, will act on the disk 313 to resist the radialtranslation along direction 358, thus tending to constrain thetranslation movement of disk 313.

Constraint tendons may be fixed in place via, for example, weldingconstraint tendons in place, crimping constraint tendons to anotherobject, or by other methods familiar to one of ordinary skill in theart. For instance, distal ends of constraint tendons may be fixed todisk 311 or to distal end 302 of instrument and proximal ends ofconstraint tendon(s) may be fixed to disk 315 or to instrument portion316 proximal to wrist 310. Turning to FIG. 5, which shows distalinstrument shaft portion 300 of FIG. 3 but with disks 312-314represented by only dashed lines to reveal internal components of wrist310, constraint tendons 330, 332, 334, 336 are each fixed at a proximalend of wrist 310 by a crimp 338, according to an exemplary embodiment.Crimps 338 may be located within passages of disk 315 or instrumentportion 316. Distal ends of constraint tendons 330, 332, 334, 336 alsocan be fixed by crimps (not shown) within passages of disk 311 or distalend 302 of instrument shaft distal portion 300.

According to an exemplary embodiment, constraint tendons may be fixed inplace so as to apply a tension to the constraint tendons. A tensionapplied to a fixed constraint tendon when a wrist is in thesubstantially straight or neutral configuration as shown in theexemplary embodiment of FIG. 3 (which may also be referred to as apre-loaded tension) may range, for example, from approximately 0 poundsto 5 pounds, in various exemplary embodiments. When the tension isapproximately 0 pounds in the substantially straight or neutralconfiguration, for example, a constraint tendon may apply a force to thedisks of a wrist to constrain motion of the disks once the wrist isarticulated. According to another exemplary embodiment, a tensionapplied to a fixed constraint tendon when a wrist is in thesubstantially straight or neutral configuration, as shown in theexemplary embodiment of FIG. 3, may range, for example, fromapproximately 3 pounds to approximately 5 pounds. As constraint tendonsare fixed at ends of wrist, according to an exemplary embodiment,constraint tendons do not extend through a shaft of an instrument to aforce transmission mechanism and are not actuated by the forcetransmission mechanism, which may simplify the force transmissionmechanism, facilitate control, and conserve instrument space.

According to an exemplary embodiment, constraint tendons may be twisted(e.g., in a substantially helical pattern) through at least a portion ofa wrist. Although wrist 310 includes four constraint tendons 330, 332,334, 336, as shown in the exemplary embodiment of FIG. 5, the presentdisclosure contemplates other numbers of constraint tendons, such astwo, three, five, six, seven, eight, or more constraint tendons.According to an exemplary embodiment, constraint tendons 330, 332, 334,336 extend along a helical path from disk 315 to disk 311, as shown inFIG. 5, so that each of the constraint tendons 330, 332, 334, 336traverses a helical path.

According to an exemplary embodiment, constraint tendons of theexemplary embodiments described herein may continuously curve whenextending along helical paths and follow a substantially twisted path.For instance, constraint tendons may extend along a helical path with asubstantially constant radius of curvature or with a radius of curvaturethat differs in various sections along the constraint tendons. Accordingto another exemplary embodiment, constraint tendons extending along ahelical path may include one or more straight path sections in which theconstraint tendons extend substantially straight. For instance,constraint tendons may include straight sections that extend betweendisks, such as, for example, between each of disks 311-315. Constrainttendons may extend along a helical path by including a series ofsubstantially straight sections angled relative to one another toprovide the helical path, according to an exemplary embodiment.According to another exemplary embodiment, constraint tendons mayinclude a mixture of one or more curved sections in which the constrainttendons curve and one or more substantially straight sections. Forinstance, constraint tendons may be curved when passing through disksand substantially straight between disks. According to an exemplaryembodiment, the slope of constraint tendons, as the constraint tendonsextend along a longitudinal direction of an instrument, may besubstantially constant or may vary. For instance, the slope ofconstraint tendons may vary from one curved section to another, from onestraight section to another, or between straight and curved sections ofa constraint tendon as the constraint tendon extends along alongitudinal direction of an instrument. Regardless of whether thehelical paths followed by the constraint tendons contain some straightsections or varying degrees of curvature, the helical path can beconsidered approximately helical such that the constraint tendons extendover some angular extent when projected onto a plane.

An angular extent of a helical path of a constraint tendon is furtherillustrated in the exemplary embodiment of FIG. 6. As shown in FIG. 6, ahelically twisted tendon extends in a helix path 400 around alongitudinal axis 408 (at a centerline of the helical path 400) from afirst end 402 to a second end 406. To show the angular extent of thehelical path 400, the helical path 400 can be projected onto a plane 401perpendicular to axis 408. The projection is an arc 410 having a radiusof curvature 403 corresponding to the radius of curvature of twistedpath 400, with points on arc 410 corresponding to locations on helicalpath 400. For instance, point 412 on arc 410 corresponds to a first end402 of the helical path and point 414 on arc 410 corresponds to a point404 approximately halfway along the length of the helical path. Althoughhelical path 400 is depicted in the exemplary embodiment of FIG. 6 ashaving a substantially continuous radius of curvature 403, helical path400 (and therefore arc 410) also may include sections having differentcurvature and may include one or more straight sections, as discussedabove. Therefore, when a helical path is discussed in the exemplaryembodiments herein, the helical path may have a helical shape with asubstantially continuous radius of curvature or the helical path mayinclude sections with differing radii of curvature, including curvedsections with differing radii of curvature and/or straight sections.

As shown in FIG. 6, an angular extent 420 between point 412 and point414 on arc 410, relative to centerline 408 (also be projected onto plane401), is approximately 180°. Thus, when the angular extent of a helicalpath is discussed in the exemplary embodiments herein, the angularextent can be determined according to angular extent 420 relative tocenterline 408, as shown in FIG. 6. Further, because helical path 400completes a full 360 degree helical twist from first end 402 to secondend 406, point 412 on arc 410 corresponds to both first end 402 andsecond end 406, with the angular extent 422 between first end 402 andsecond end 406 being 360 degrees. Thus, in the exemplary illustration ofFIG. 6, arc 410 forms a complete circle. However, in embodiments inwhich a helical path does not complete a 360 degree twist, arc 410 willnot complete a circle because the angular extent of the helical path isless than 360 degrees.

According to an exemplary embodiment, constraint tendons 330, 332, 334,336 extend along a helical path so that constraint tendons 330, 332,334, 336 have an angular extent of approximately 360 degrees along theentire length of wrist 310. For instance, constraint tendons 330, 332,334, 336 may extend along a helical path having an angular extent ofapproximately 90 degrees between each disk 311-315 of wrist 310 whenwrist 310 includes four disks 311-315. In other words, constrainttendons 330, 332, 334, 336 may be extend along a helical path having anangular extent of approximately 90 degrees each between disk 315 anddisk 314, between disk 314 and disk 313, between disk 313 and disk 312,and between disk 312 and disk 311. In another exemplary embodiment, awrist may include six disks with the constraint tendons of the wristextending along a twisted path having an angular extent of approximately60 degrees between each disk of the wrist, with a total angular extentalong the entire wrist being 360 degrees for the constraint tendons.Thus, constraint tendons may extend along a twisted path having anangular extent equaling the total angular extent across the wrist forthe constraint tendon (e.g., 360 degrees), divided by the number ofdisks of the wrist, according to an exemplary embodiment. However,various exemplary embodiments of the present disclosure contemplate theconstraint tendons of a wrist may extend along a helical path to otherangular extents. For example, constraint tendons may extend along ahelical path such that the amount of angular extent differs betweendiffering disks of a wrist. Such a configuration may provide wrist thatachieves differing degrees of bending (articulating) along differingsections along the length of the wrist. Further, the total angularextent of constraint tendons may be an integer multiple of 360 degrees,such as when an instrument includes an integer multiple of wrists,according to an exemplary embodiment. Further constraint tendons mayextend along a helical path a different amount than approximately 90degrees between disks, such as, for example, approximately 180 degrees,according to an exemplary embodiment. According to an exemplaryembodiment, the constraint tendons may extend along a helical path in anamount described in the exemplary embodiments of U.S. ProvisionalApplication No. 61/943,084, filed on Feb. 21, 2014, which is herebyincorporated by reference in its entirety.

To illustrate the helical path of a constraint tendon, a side view of awrist 360 including disks 361-365 is shown in the exemplary embodimentof FIG. 7A with the helical path 366 of a single constraint tendonthrough disks 361-365 shown in dashed lines to facilitate viewing of thehelical path, although differing numbers of constraint tendons arecontemplated, as discussed in regard to the exemplary embodiment of FIG.3 above. Further, respective cross-sections 371-375 through disks361-365, shown in FIG. 7B, illustrate the position of the path 366 ofthe constraint tendon through disks 361-365. In the exemplary embodimentof FIG. 7A, the path 366 of the constraint tendon follows a helical pathhaving an angular extent of approximately 90 degrees from disk to disk,although other angular extents may be utilized, as discussed above.

Twisting constraint tendons so as to traverse a helical path through atleast a portion of a wrist provides advantages other than constrainingthe motion of the wrist to provide accurate control of the movement andshape of the wrist. For instance, constraint tendons may extend along ahelical path so that constraint tendons are positioned in differinglocations than joints between disks of a wrist. As shown in theexemplary embodiment of FIG. 3, wrist 310 includes a joint 322 betweendisks 311 and 312 that permits disks 311 and 312 to rotate (i.e., pivot)relative to one another about axis 350 in direction 351. Constrainttendons 334 and 336 extend between disks 311 and 312 so that constrainttendons 334 and 336 do not physically pass through joint 322. In otherwords, constraint tendons 334 and 336 are offset from joint 322, asshown in FIG. 3. As a result, joint 322 need not include hollow passagesfor constraint tendons 334 and 336, permitting joint 322 to be a smallersize while also functioning to bear compressive loads between disks 311and 312.

Constraint tendons may follow twisted paths to avoid joints connectingdisks so the constraint tendons are offset or otherwise adjacent to thejoints. For instance, constraint tendons 334 and 336 may extend betweendisks 311 and 312 on an open side of wrist 310 where an aperture 340 isprovided between disks 311 and 312 (when wrist 310 is in the straight orneutral configuration shown in FIG. 3) so that constraint tendons 334and 336 do not pass through joint 322, which would otherwise lead toweakening of joint 322 due to passages for constraint tendons 334 and336 through joint 322. According to an exemplary embodiment, joint 322may include a surface 304 in disk 311 and a surface 306 in disk 312 thatcontact one another to form a rotating joint between disk 311 and disk312. Constraint tendons 334 and 336 may extend between disks 311 and 312such that constraint tendons 334 and 336 do not pass through surfaces304 and 306, which would otherwise require passages through andweakening of surfaces 304 and 306. For instance, constraint tendons 334and 336 may be offset from surfaces 304 and 306 of joint 322 in atransverse direction.

Similarly, constraint tendons 330 and 334 may extend between disks 313and 312 so constraint tendons 330 and 334 do not pass through joint 324,which permit disks 313 and 312 to rotate relative to one another aboutaxis 352 in direction 352; constraint tendons 330 and 332 may extendbetween disks 314 and 313 so constraint tendons 330 and 332 do notphysically pass through joint 326, which permit disks 314 and 314 torotate relative to one another about axis 354 in direction 355; andconstraint tendons 332 and 336 may extend between disks 314 and 315 soconstraint tendons 332 and 336 do not physically pass through joint 328,which permit disks 315 and 314 to rotate relative to one another aboutaxis 356 in direction 357.

Disks of a wrist may be configured to locate and/or direct constrainttendons as they pass through the disks. For example, it may be desirableto avoid having the constraint tendons passing through joints betweendisks. Turning to FIG. 8A, a perspective view is shown of an exemplaryembodiment of a disk 500. Disks 311-315 of wrist of FIGS. 3 and 5 may beconfigured according to disk 500. Disk 500 includes one or more drivetendon apertures 510 through which drive tendons may pass. For instance,when disks 311-315 of the exemplary embodiment of FIGS. 3 and 5 areconfigured according the exemplary embodiment of disk 500, actuationelements 320 may extend through drive tendon apertures 510. Further,disk 500 may include one or more constraint tendon apertures 512 throughwhich constraint tendons may pass. Thus, when disks 311-315 of wrist 310are configured according to the exemplary embodiment of disk 500,constraint tendons 330, 332, 334, 336 may extend through constrainttendon apertures 512. Disk 500 may further include a central aperture516 through which one or more flux conduits (e.g. electrical conductorsor optical fibers) or other actuation elements, such as for an endeffector, may extend.

Because constraint tendons extend in a helical path along at least aportion of a wrist, constraint tendons may sweep (e.g., move in adirection 530 relative to disk 500) through a larger circumferentialextent than drive tendons, which extend in a substantially straightdirection between the disks of a wrist, when the wrist is actuated toarticulate and bend. Constraint tendon apertures 512 may be locatedclose to an outer periphery 502 of disk 500 because less sweep ofconstraint tendons may occur when the constraint tendons are positionedfurther away from a central aperture 516 of disk. Although some sweep ofconstraint tendons may still occur, locating constraint tendon apertures512 closer to periphery 502 also provides more space for centralaperture 516 and/or joint structures 520 of disk 500. As shown in theexemplary embodiment of FIG. 8A, drive tendon apertures 510 andconstraint tendon apertures 512 may both be located close to outerperiphery 502 of disk 500 in similar positions along a radial directions515 relative to central aperture 516.

According to another exemplary embodiment, drive tendon apertures 510and constraint tendon apertures 512 may be located at differentlocations along radial directions 515. For example, constraint tendonapertures 512 may be radially offset from drive tendon apertures 510 sothat constraint tendon apertures 512 are located along radial directions515 closer to central aperture 516 than drive tendon apertures 510. As aresult, constraint tendons extending through constraint tendon apertures512 may be located radially inward of joint structures 520 of disk 500so that the constraint tendons do not interfere with joint structures520. In another example, constraint tendon apertures 512 for constrainttendons extending along differing helical path directions can be offsetfrom one another. For example, apertures for constraint tendons 330extending along a helical path in a first direction 342 (such as, forexample, in a left-handed direction in a proximal to distal direction)in FIG. 5 and apertures for constraint tendons 334 extending along ahelical path in a second direction 344 (such as, for example, in aright-handed direction in the proximal to distal direction) can beoffset to minimize or avoid friction between the constraint tendonsextending in differing directions.

According to an exemplary embodiment, drive tendon apertures 510 may belocated at a distance of, for example, about 0.095 inches to about 0.100inches from central aperture 516 along radial direction 515 andconstraint tendon apertures may be located at a distance of, forexample, about 0.080 inches to about 0.085 inches from central aperture516 along radial direction 515. In an exemplary embodiment in whichconstraint tendon apertures 512 are radially offset from drive tendonapertures 510, a disk 500 may include four constraint tendon apertures512, as shown in the exemplary embodiment of FIG. 8A, for acorresponding number of constraint tendons, although other numbers ofconstraint tendon apertures 512 and constraint tendons may be utilized.For instance, three, five, six, seven, eight, or more constraint tendonsapertures 512 and constraint tendons may be used. According to anexemplary embodiment, the number of constraint tendons and constrainttendon apertures 512 used may equal, for example, the number joints in awrist including disk(s) 500 plus one.

To accommodate the sweep of constraint tendons, constraint tendonapertures 512 may have, for example, a different shape than drive tendonapertures 510. For instance, drive tendon apertures 510 may have asubstantially circular transverse cross-section, while constraint tendonapertures 512 may have elongated and non-circular cross-sections, suchas being elongated along direction 530. For example, constraint tendonapertures 512 may have an oval, elliptical or kidney shape. In anotherexample, constraint tendon apertures 512 may span along direction 530 toa differing extent than drive tendon apertures 510. For instance,constraint tendon apertures 512 may span to a greater extent alongdirection 530 than drive tendon apertures 510. According to an exemplaryembodiment, drive tendon apertures 510 may have a diameter ranging from,for example, about 0.020 inches to about 0.025 inches and constrainttendon apertures 512 may have a length along circumferential direction530 of, for example, about 0.020 inches to about 0.025 inches, withdrive constraint tendon apertures 512 being equal to or greater inlength or diameter than drive tendon apertures 510. Due to the elongatedshape and/or circumferential length of constraint tendon apertures 512,constraint tendon apertures 512 may better accommodate the sweep ofconstraint tendons that extend through constraint tendon apertures 512as a wrist is actuated to bend from its neutral position.

According to an exemplary embodiment, disk 500 may include a recessedsurface portion 514 located adjacent to and extending from a constrainttendon aperture 512. Because constraint tendons extend along helicalpaths along at least a portion of a wrist, constraint tendons may sweepalong circumferential direction 530 and against a circumferential edge513 of constraint tendon apertures 512. By providing a recess surfaceportion 514 adjacent to constraint tendon aperture 512, the sweep of aconstraint tendon may be further accommodated, such as by permitting theconstraint tendon to enter into recess surface portion 514 when theconstraint tendon sweeps against a circumferential edge 513 of aconstraint tendon aperture 512. Recess surface portion 514 may have, forexample, an elongated shape with a depth that is substantially constantor a depth that varies, such as, for example, by decreasing in adirection away from a constraint tendon aperture that the recess surfaceportion 514 is adjacent to. The latter therefore providing a ramp-likefeature from aperture 512 up to the surface of disk 500. According to anexemplary embodiment, recess surface portions 514 may slope at an angle,for example, ranging from about 20 degrees to about 30 degrees.

According to an exemplary embodiment, disk 500 may include jointstructures 520 to form joints between adjacent disks. Joint structures520 may be configured in various ways. For example, joint structures 520may include cycloidal shapes, as described in U.S. Pat. No. 8,887,595,published Nov. 18, 2014, which is hereby incorporated by reference inits entirety or may be configured according to the exemplary embodimentsof U.S. Pat. No. 8,911,428, published Dec. 16, 2014, which is herebyincorporated by reference in its entirety. Joints 322, 324, 326, 328 ofthe exemplary embodiment of FIG. 3 may be configured like jointstructures 520. According to an exemplary embodiment, a joint structure520 may include a projection 522 (or tooth). Projection 522 may beinserted in a corresponding recess of an adjacent disk, such as disk 540shown in the exemplary embodiment of FIG. 8B, which may include a recess552 having a corresponding shape and configured to receive projection522 of disk 500. According to an exemplary embodiment, recess 552 mayform one or more pins to intermesh with projection 522. Thus, in a pairof adjacent disks, a first disk may include one or more projections (orteeth) and a second disk may include one more recesses (or pins)configured to receive the projection(s).

According to an exemplary embodiment, a joint structure 520 of disk 500of the exemplary embodiment of FIG. 8A may further include a projection524 configured to contact a corresponding projection of an adjacentdisk, such as projection 554 of disk 540 in the exemplary embodiment ofFIG. 8B. As a result, projection 524 may serve as a compression loadbearing surface between adjacent disks. Because constraint cables arelocated separately from and directed away from joint structures 520,including load bearing projections 524, joint structures 520 are notweakened by constraint cable apertures extending through jointstructures 520. Thus, joint structures 520, including load bearingprojections 524 may be made larger, which increases the loads that maybe accommodated by a wrist including disks like disk 500, making thewrist stronger.

Another advantage provided by extending constraint tendons along helicalpaths is the substantial conservation of lengths of constraint tendonswhen a wrist is actuated to articulate (e.g., bend). When disks 313, 314are actuated to pivot relative to one another about axis 354 indirection 355 in FIG. 3, constraint tendons 330 and 332 may change inlength between disks 313 and 314. For example, constraint tendons 330and 332 may experience a positive change in length between disks 313 and314 when disks 313 and 314 are rotated relative to one another aboutaxis 354 in a direction away from the side of wrist 310 that constrainttendons 330 and 332 are on between disks 313 and 314. Conversely,constraint tendons 330 and 332 may experience a negative change inlength between disks 313 and 314 when disks 313 and 314 are rotatedrelative to one another about axis 354 in a direction toward the side ofwrist 310 that constraint tendons 330 and 332 are on between disks 313and 314. Other constraint tendons experience similar positive ornegative changes in length between other disks when wrist 310 isactuated. Changes in length of constraint tendons may affect thefunction of constraint tendons to constrain the motion of wrist 310,such as by introducing slack in constraint tendons.

A twisting path for a constraint tendon through an articulatable member,such as a wrist, may be selected to address changes in length ofconstraint tendons. According to an exemplary embodiment, passiveconstraint tendons may extend along a helical path along at least aportion of a wrist to substantially conserve the length of theconstraint tendons over the entire length of the wrist. A constrainttendon may passively constrain movement of an articulatable memberwithout the use of an actuator, such as a force transmission mechanismand control algorithms controlling the same. For example, in variousexemplary embodiments, the movement of disks of a jointed link structuremay be passively constrained by constraint members that are notactuatable by an external drive or transmission mechanism. To achievethis, a passive constraint tendon may extend along a helical path sothat when an articulated member including the constraint tendon is bent,such as in a pitch and/or yaw motion, the constraint tendon experiencesa positive or negative change in length between a first pair of adjacentdisks and experiences a corresponding, and opposite, negative orpositive change in length between a second pair of adjacent disks thatsubstantially cancels the change in length from the first pair ofadjacent disks. As a result, the length of the constraint tendon issubstantially conserved. Further, because ends of the constraint tendonare fixed at opposite ends of the articulatable member, which fixes thelength of the constraint tendon, the bending motion (e.g., a pitchand/or yaw motion) is permitted because the bending motion does notsubstantially result in a change in length of the constraint tendon. Incontrast, a translation motion, such as to laterally move a wrist intoan S-shape, may be substantially prevented because the translationmotion does not result in a conservation of the length of the constrainttendon but the fixed ends of the constraint tendon substantially preventa change in length of the constraint tendon.

Turning to the exemplary embodiment of FIG. 5, constraint tendons 332and 336 experience a negative change in length when disks 315 and 314are rotated about axis 356 in direction 357 toward each other on theside of wrist 310 that constraint tendons 332 and 336 are located.Constraint tendons 332 and 336 extend along a helical path through wrist310 so that constraint tendons 332 and 336 extend between disks 313 and312 on an opposite side of wrist 310 from where constraint tendons 332and 336 extend between disks 315 and 314. Thus, when disks 313 and 312are rotated about axis 352 along direction 353 in substantially the sameway as disks 315 and 314, constraint tendons 332 and 336 experience apositive change in length between disks 313 and 312 in an amount thatsubstantially cancels the negative change in length between disks 315and 314, thereby substantially conserving the length of constrainttendons 332 and 336. Similarly, when wrist 310 is actuated in theopposite direction so that constraint tendons 332 and 336 experience apositive change in length between disks 315 and 314 and a negativechange in length between disks 313 and 312, the lengths of constrainttendons 332 and 336 are still substantially conserved. Constrainttendons 330 and 334 also may extend along a helical path so that changesin length of constraint tendons 330 and 334 between disks 315 and 314substantially cancel changes in length of constraint tendons 330 and 334between disks 313 and 312. In addition, constraint tendons 330, 332,334, 336 extend along a helical path so that change in length ofconstraint tendons 330, 332, 334, 336 between disks 314 and 313substantially cancel changes in length constraint tendons 330, 332, 334,336 between disks 312 and 311.

According to an exemplary embodiment, when the bend axes 350, 352, 354,356 of wrist 310 alternate in different (e.g., orthogonal) directions,as shown in FIG. 3, constraint tendons 332 and 336 may extend in ahelical path over an angular extent of approximately 180 degrees fromthe position of constraint tendons 332 and 336 at a location betweendisks 315 and 314, such as, for example, at location 370 shown in FIG.3, to the position of constraint tendons 332 and 336 at a locationbetween disks 313 and 312, such as, for example, at location 372 shownin FIG. 3. In this way, constraint tendons 332 and 336 are located onopposite sides of wrist 310 to facilitate conservation of the lengths ofconstraint tendons 332 and 336. As noted above, constraint tendons 330,332, 334, 336 may extend in a helical path over an angular extent ofapproximately 90 degrees from disk 311 to disk 312, from disk 312 todisk 313, and so on, thus providing a helical path having an overallangular extent of approximately 180 degrees from disk 311 to disk 313.Similarly, constraint tendons 330 and 334 may extend along a helicalpath having an angular extent of approximately 180 degrees from theposition of constraint tendons 330 and 334 at a location between disks315 and 314 to the position of constraint tendons 330 and 334 at alocation between disks 313 and 312. In addition, constraint tendons 330,332, 334, 336 may extend along a helical path having an angular extentof approximately 180 degrees from the position of constraint tendons330, 332, 334, 336 at a location between disks 313 and 314 to theposition of constraint tendons 330, 332, 334, 336 at a location betweendisks 312 and 311.

According to an exemplary embodiment, by fixing constraint tendons 330,332, 334, 336 at opposite ends of wrist 310, bend angles of similarjoints of wrist will be substantially the same. By providing a wristthat has substantially the same bend angles for similar joints, motionsof the wrist may be more easily controlled and may be smoother.According to an exemplary embodiment, when wrist 310 is actuated to bendtoward the side of wrist 310 where constraint tendons 332, 336 extendbetween disks 315 and 314, disks 315 and 314 rotate relative to oneanother about axis 356 to substantially the same degree that disks 313and 312 rotate relative to one another about axis 352. This is becauseaxes 356 and 352 are substantially parallel to one another. Similarly,when wrist 310 is actuated to cause rotation between disks 311 and 312about axis 350, disks 313 and 314 also rotate about axis 354 tosubstantially the same degree.

According to an exemplary embodiment, all of the constraint tendons of awrist may extend in helical paths in the same circumferential directionfrom a distal disk (e.g., disk 311) to a proximal disk (e.g., disk 315).However, in such an exemplary embodiment, one or more of the constrainttendons may pass through one or more joint structures between adjacentdisks, which may result in weakening of the joint structure(s). Toaddress this, constraint tendons can be routed to extend along helicalpaths in different directions. For instance, one constraint tendon mayextend along a twisted path in a right-handed or left-handed directionalong the proximal-distal direction of an instrument and anotherconstraint tendon may extend along a twisted path in the other of theleft-handed or right-handed direction along the proximal-distaldirection of the instrument. As shown in the exemplary embodiment ofFIG. 5, constraint tendon 330 extends along a helical path in a firstdirection 342 (such as, for example, in a left-handed direction in aproximal to distal direction) and constraint tendon 334 extends along ahelical path in a second direction 344 (such as, for example, in aright-handed direction in the proximal to distal direction) differingfrom first direction 344 from disk 311 to disk 315. For instance, firstdirection 342 and second direction 344 are in directions opposite to oneanother. By extending constraint tendons 330 and 334 along helical pathsin respective directions 342 and 344 from disk 311 to disk 315,constraint tendons 330 and 334 can extend between disks 311-315 withoutpassing through any of joints 322, 324, 326, 328.

Similarly, constraint tendons 332 and 336 extend along helical paths inrespective opposite directions 344 and 342 from disk 311 to disk 315 sothat constraint tendons 332 and 336 do not physically pass through anyof joints 322, 324, 326, 328. According to an exemplary embodiment, atleast a portion of both constraint tendons 330 and 336 extend alonghelical paths in direction 342 from disk 311 to disk 315. According toan exemplary embodiment, at least a portion of both of constrainttendons 334 and 332 extend along helical paths in direction 344 fromdisk 311 to disk 315. In other words, when wrist 310 includes fourconstraint tendons 330, 332, 334, 336, two of the constraint tendons mayextend along a helical path along direction 342 from disk 311 to disk315 and the other two constraint tendons may extend along a helical pathin direction 344 from disk 311 to disk 315.

One consideration in configuring constraint tendons is the amount offriction between the constraint tendons and components of a wrist, whichcan impact motion of the wrist, power needed to actuate the wrist,and/or wear on the wrist components. For instance, in wrists that usemultiple sets of actuation members to actively constrain a wrist, theactuation members typically extend along a straight path through theinstrument and wrist, with bending occurring as the wrist bends. Inlight of the increased amount of friction that can result betweenconstraint tendons and wrist components due to a helical path ofconstraint tendons as compared to, for example, a straight path,constraint tendons may extend along helical paths in a way to helpminimize friction.

According to an exemplary embodiment, extending constraint tendons 330,332, 334, 336 along helical paths to have an angular extent ofapproximately 90 degrees as the tendons traverse between each pair ofdisks 311-315 does not result in a significant increase in friction incomparison to conventional wrists that utilize multiple sets of straighttendons to constrain joint motion. This is because although constrainttendons 330, 332, 334, 336 extend along helical paths, a wrap angle,which can be used to determine the amount of friction between constrainttendons 330, 332, 334, 336 and wrist components, is not significantlygreater than a wrap angle for straight tendons used to constrain jointmotion in conventional wrists. Friction between a tendon and itssupporting surface(s) may be represented by the capstan equation,T_(load)=T_(hold) ^(μφ), in which T_(hold) is tension applied to thetendon (such as a preloaded tension), μ is the coefficient of frictionbetween the tendon and support surface(s), φ is the total angle swept bythe twist of the tendon, and T_(load) is the force between the tendonand supporting surface(s). Twisting a tendon through a large angle of φthus results in a large T_(load) force between the tendon and thesupport surface(s). In an exemplary embodiment, using a helical pathhaving an angular extent of approximately 90 degrees between each ofneighboring disks 311-315 may provide a wrap angle having, for example,an angular extent of approximately 40 degrees to approximately 70degrees at, for example, three bend locations 345, 346, 347 shown in theexemplary embodiment of FIG. 5.

The various wrist exemplary embodiments described herein may includedisks arranged in various configurations. For example, the configurationshown in the exemplary embodiment of FIG. 3 may be referred to as an“ABAB” wrist due to the alternating orthogonal directions of axes 350,352, 354, 356. In other exemplary embodiments, a wrist can utilize aconfiguration in which axes of rotation between disks do not alternatein orthogonal directions but instead follow an “ABBA” configuration sothat two consecutive axes (e.g., axes of middle disks) extend insubstantially the same direction and are “bookended” by axes that extendin the same direction but are orthogonal to the two consecutive axes.

An ABBA configuration acts similarly to a constant velocity joint, whichmay be desirable when rolling motions are transmitted through the wrist.For instance, when a wrist is used in an instrument and a rolling motionis input to the instrument shaft, the rolling motion is transmittedthrough the wrist, causing a distal end of the instrument, which mayinclude an end effector, to roll as well. Because a wrist includes oneor more joints, the wrist acts like an input and output shaft of avehicle drive train connected via one or more joints. As one of ordinaryskill in the art is familiar with, when an angle exists between theinput and output shaft of a vehicle drive train, a variation in speedoccurs between the input shaft and output shaft, which is undesirable. Awrist with an ABBA mechanism addresses this consideration by acting likea constant velocity joint, similar to a double Cardan joint, with thetwo A joints having substantially the same angle and the two B jointshaving substantially the same angle, thereby resulting in a substantialcancellation of speed variation between the input and output sides.Thus, an ABBA wrist can minimize or eliminate a variation in speedbetween an input and output side of the wrist for rolling motionsapplied to an instrument shaft.

Although an ABBA configuration minimizes or eliminates variation inspeed between an input and output side of a wrist for rolling motion, anABAB configuration, such as the exemplary embodiment of FIG. 3, may beused to advantageously provide a wrist 310 in which constraint tendons330, 332, 334, 336 extend along helical paths a minimal amount per disk311-315, in comparison to an ABBA configuration, while alsosubstantially conserving the lengths of constraint tendons 330, 332,334, 336 and positioning constraint tendons 330, 332, 334, 336 so thatconstraint tendons 330, 332, 334, 336 do not pass through jointsconnecting disks. As a result, precise control of movement of the wrist310 may be obtained with smooth motions and joints connecting disks311-315 may be small.

Although a wrist mechanism with an ABAB configuration provides adisadvantage of naturally providing a speed variation between its inputand output side, extending constraint tendons along helical pathsthrough at least a portion of a wrist and fixing the constraint tendonsat opposite ends of the wrist provide significant advantages that atleast offset this disadvantage. Further, any speed variation may becompensated for by control systems that regulate input rotational speedto the wrist to accomplish rolling, such as by varying an input speedaccording to a bend angle of the wrist to compensate for variation inspeed.

Turning to FIG. 9, one exemplary embodiment of an ABBA wrist thatutilizes constraint tendons is depicted. In FIG. 9, wrist 600 includesdisks 611-615 arranged in an ABBA joint configuration. In particular, ajoint 640 between disks 611 and 612 can permit rotation of disks 611 and612 about axis 620 in direction 621, a joint 642 between disks 612 and613 can permit rotation of disks 612 and 613 about axis 622 in direction623, a connection 644 between disks 613 and 614 can permit rotation ofdisks 613 and 614 about axis 624 in direction 625, and a connection 646between disks 614 and 615 can permit rotation of disks 614 and 615 aboutaxis 626 in direction 627. As shown in the exemplary embodiment of FIG.9, axes 620 and 626 may extend in substantially the same direction, axes622 and 624 may extend in substantially the same direction, and axes 620and 626 may be substantially orthogonal to axes 622 and 624, therebycreating the ABBA joint axis configuration (or arbitrarypitch-yaw-yaw-pitch rotation of the disk pairs).

Wrist 600 further includes constraint tendons fixed at opposite ends ofwrist 600. As shown in the exemplary embodiment of FIG. 9, wrist 600includes four constraint tendons 630, 632, 634, 636, although othernumbers of constraint tendons may be used. Unlike the exemplaryembodiment of FIG. 3, in which constraint tendons extend along a helicalpath having an angular extent of approximately 90 degrees between eachpair of disks, in the exemplary embodiment of FIG. 9, constraint tendons630, 632, 634, 636 are substantially straight from disk 611 to 612, fromdisk 612 to disk 613, from disk 613 to disk 614, and from disk 614 todisk 615, but extend along a helical path having an angular extent ofapproximately 180 degrees across disk 613, such as, for example, along atwisted path or another path across disk 613 to reach a point 180degrees away. As a result, the lengths of constraint tendons 630, 632,634, 636 may be conserved when wrist 600 is articulated (e.g., bent). Inother words, instead of extending along a helical path with an angularextent of approximately 90 degrees for all joints, constraint tendons inan ABBA configuration would have extend along a helical path with anangular extent of approximately 180 degrees between the B type jointsand a helical path with an angular extent of approximately 0 degreesacross the A type joints.

This is further illustrated in FIG. 10, which is a cross-sectional viewalong lines 10-10 in FIG. 9. As shown in FIG. 10, each of constrainttendons 630 and 632 may traverse an angular extent of approximately 180degrees across disk 613. Constraint tendons 634 and 636 would have thesame angular extent as constraint tendons 630 and 632 although enteringand exiting disk 613 at different locations. Because constraint tendons630, 634 and constraint tendons 632, 636 respectively cross over oneanother, constraint tendons 630, 634 and constraint tendons 632, 636 aredepicted in the same location in the cross-sectional view of theexemplary embodiment of FIG. 10. Thus, although the ABBA configurationcould minimize speed variation between its input and output sides forrotation (roll) motion, the constraint tendons may pass through thecenter of the wrist. Although wrist 600 may be configured so constrainttendons 630, 632, 634, 636 are helically twisted along paths extendingalong a periphery of disk 613, such a design may be less practical thanextending the paths across the center of disk 613.

For instance, when wrist 600 uses the disks 500 and 540 of the exemplaryembodiment of FIGS. 8A and 8B, constraint tendons would pass through acentral lumen provided by central aperture 516 of disks, thuspotentially interfering with any actuation members that may otherwisepass through the central lumen. Thus, if the central lumen wouldotherwise receive an actuation member for an end effector, the endeffector actuation member would have to be routed through a differentlumen and may need a different design when not located in the centrallumen. Further, because the angular extent of the helical path ofconstraint tendons 630, 632, 634, 636 is greater, the wrap angle forconstraint tendons 630, 632, 634, 636 is also greater, which results ina larger amount of friction between constraint tendons 630, 632, 634,636 in comparison to a wrist with an ABAB configuration. A wrist 600with an ABAB configuration may be used in, for example, relatively largediameter instruments subjected to relatively small loads. According toanother exemplary embodiment, constraint tendons 630, 632, 634, 636 maybe configured to extend along paths that do not pass through the centerof a central lumen. However, such an embodiment would result in a largerwrap angle for constraint tendons 630, 632, 634, 636, which can lead toincreased friction between constraint tendons 630, 632, 634, 636 anddisk 613.

Although the exemplary embodiments of FIGS. 3 and 9 depict wristsincluding four joints, the wrists and other jointed link structuresarticulatable members according to the exemplary embodiments describedherein are not limited to four joints. For example, a wrist and otherarticulatable members may have two disks, three disks, five joints, sixjoints, eight joints, or a greater number of joints.

As discussed above with regard to the exemplary embodiments of FIGS. 3,4, 9, and 10, a jointed link structure, such as a wrist, may include aseries of connected disks with tendons to provide a structure forconstraining the motion of the wrist. However, other articulatablemembers, used as wrists or otherwise, in accordance with the variousexemplary embodiments of the present disclosure can include otherstructures. Turning to FIG. 11, an exemplary embodiment of anarticulatable member 700 is shown in which a braided structure 710replaces the disks and forms the main body of the articulatable member700. As in other exemplary embodiments described herein, thearticulatable member 700 can be a wrist, part of a parallel motionmechanism, or other articulatable component of an instrument, such as asurgical instrument. FIG. 11 shows articulable member 700 in a straight(i.e., non-bent) configuration.

According to an exemplary embodiment, the braided structure 710 may havea hollow cylindrical or tubular shape defining a central passage forinstrument components. FIG. 12 shows an enlarged view of portion FIG. 12of braided structure 710 in FIG. 11. As shown, braided structure 710 mayinclude plaits 712 interwoven with one another. In braided structure710, each of plaits 712 form a helical shaped structure about acenterline of the braided structure 710 extending between the proximalend 702 and the distal end 704 of articulable member 700, the centerlinedefining a helical axis. In one aspect (not shown), each of plaits 712make one revolution about the helical axis in the distance between disk721 and disk 722.

It should be understood that FIG. 11 and enlarged view FIG. 12 are sideview depictions of the articulable member 700 including braidedstructure 710. FIG. 12 shows an enlarged view of a portion of braidedstructure 710, and more specifically, shows the geometric relationshipof the interwoven plaits 712. The warp 711 and weft 713 directions arean attempt to express in two dimensions the helix angles of the plaits712. The portion of braided structure 710 shown in FIG. 12 is a small,approximately flat section of plaits 712 interwoven with one another.The warp 711 and weft 713 directions shown in FIG. 12 show theapproximate angles of the plaits relative to an imaginary axial lineextending along the length of the instrument on the outside surface ofbraided structure 710 (i.e., the line formed by contacting a tangentplane with the curved outer surface of braided structure 710, with thetangent plane being substantially parallel to the centerline of braidedstructure 710). In one aspect, the angle between the warp 711 directionand the imaginary axial line is the same as to the angle between theweft 713 direction and the imaginary axial line. Stated another way, thehelix angle of the plaits 712 aligned with the warp 711 direction is thesame as the helix angle of the plaits 712 aligned with the weft 713direction, the two groups of plaits differing only in handedness oftheir helical shapes (e.g., one direction of plaits 712 being along aright-handed helical direction and another direction for plaits 712being along a left-handed helical direction). Such a plait configurationmay produce a braided structure 710 with substantially symmetricalbending stiffness about the centerline of the braided structure 710.

Each plait 712 may be formed by a plurality of filaments 714 that extendalong the warp 711 or weft 713 directions. Plaits 712 may have agenerally rectangular structure with substantially flat surfaces thatform an exterior surface 708 of braided structure 710, as shown in FIGS.11 and 12. However, plaits may have other shapes, such as a circularcross-section, oval cross-section, or other shapes. Filaments 714 maybe, for example, monofilaments of nylon or other flexible and strongmaterial and may have a diameter ranging from, for example, about 0.008inches to about 0.012 inches, such as, for example, about 0.010 inches.Filaments 714 may be made of a material that permits filaments 714 to beflexible, so braided structure 710 may bend when a wrist includingbraided structure is actuated, but also have a sufficient bendingstiffness to minimize or prevent buckling when compressive loads areapplied to filaments 714.

Braided structure 710 may be used to constrain the motion ofarticulatable member 700, as discussed herein, by fixing the ends ofbraided structure 710. Thus, braided structure 710 may constrain motionof articulatable member 700 instead of using constraint tendons to so,as in the exemplary embodiments of FIGS. 3 and 9. According to anexemplary embodiment, a proximal end 702 of braided structure 710 isfixed to a disk 721, which may in turn connect wrist 700 to otherinstrument components, such as a distal end of a surgical instrumentshaft, a distal end of a parallel motion mechanism, or other instrumentstructure (not shown). Similarly, a distal end 704 of braided structure710 is fixed to a disk 722, which may in turn connect articulatablemember 700 to other instrument components, such as to a proximal end ofan end effector (not shown), or other structure. Disks 721, 722 differfrom the disks of an articulatable member, such as disks 311-315 ofwrist 300 of the exemplary embodiment of FIG. 3, in that disks 721, 722are not coupled to one another, such as via joints. Thus, disks 721, 722may, according to an exemplary embodiment, serve as ends of a wrist thatmay be in turn coupled to other instrument components.

Braided structure 710 can provide relatively smooth motion forarticulatable member 700, for example, when used as a wrist, and berelatively inexpensive to manufacture. Further, similar to a wriststructure having an ABBA configuration, braided structure 710 mayminimize or eliminate a speed variation between its input and outputsides when subject to rotational (roll) motion. Braided structure 710may be actuated, for example, by applying a force, such as tension orcompression, to actuation members 730 (e.g., pull/pull or push/pullactuation members which may be coupled to and actuated by a forcetransmission mechanism, as described above with regard to the exemplaryembodiment of FIG. 4) connected to distal end 704 of braided structure710, such as to distal disk 722, to cause braided structure 710, andthus articulatable member 700, to be bent along an arc.

According to another exemplary embodiment, the proximal end 702 anddistal end 704 of braided structure need not be respectively fixed todisks but instead can be directly fixed to another instrument componentwithout the use of a disk. Turning to FIG. 14, a side view is shown of adistal portion 750 of a surgical instrument that includes a wrist 751including a braided structure 710 that forms the main body of wrist 751.Braided structure 710 may have the structure and features discussed inregard to the exemplary embodiment of FIG. 11. The proximal end 702 ofbraided structure 710 is directly fixed to a distal end 754 of asurgical instrument component 572, which may be, for example, a surgicalinstrument shaft, a distal end of a parallel motion mechanism, or otherinstrument structure. Further, the distal end 704 of braided structure710 is directly fixed to a proximal end 758 of an end effector 756, orother structure. Wrist 751 may include actuation members 760 toarticulate wrist 751, such as by applying a force, such as tension orcompression, to actuation members 751 (e.g., pull/pull or push/pullactuation members), which are in turn connected to proximal end 758 ofend effector 756 to cause wrist 751 to be bent along an arc.

Articulatable member 700 may include one or more structures to controlthe diameter of braided structure 710 so that the diameter of braidedstructure 710 does not substantially shrink or expand under load, whichmay otherwise affect the precision of the motion of braided structure710. As shown in the exemplary embodiment of FIG. 11, one or more disks720 may be provided around exterior surface 708 of braided structure 710to control the outer diameter of braided structure (i.e., control theouter diameter in a radial direction). Disks 720 differ from the disksof an articulatable member, such as disks 311-315 of wrist 300 of theexemplary embodiment of FIG. 3, in that disks 721, 722 are not coupledto one another or to disks 721 or 722, such as via joints. As shown inFIG. 11, actuation members 730 may extend through apertures 723 in disks720 to guide actuation members 730 to distal disk 722. Actuation members730 may also extend through apertures 725 in disks 721 and 722.

Although two disks 720 are shown in the exemplary embodiment of FIG. 11to facilitate viewing of braided structure 710, other numbers of disks720 may be utilized, such as, for example, one, three, four, five, six,or a greater number of disks. Braided structure 710 may further includean internal structure to control the inner diameter of braided structure710. Turning to FIG. 13, which shows a cross-sectional view ofarticulatable member 700, an internal structure 740 may be providedinside braided structure 710 to control the inner diameter of braidedstructure 710. Internal structure 740 may have the shape of a hollowcylinder or tube having a central passage 742 and may be, for example, aspring or hollow tube. Internal structure 740 may be made of metal,plastic, or other material that is strong enough to resist radialdeformation of braided structure 710 but also flexible so that internalstructure 740 may be elastically deformed when articulatable member 700and braided structure 710 are actuated and bent.

According to an exemplary embodiment, an articulatable member includinga braided structure may use other structures than disks, such as disks720 of the exemplary embodiment of FIG. 11, to control the diameter ofthe braided structure. As shown in the exemplary embodiment of FIG. 14,wrist 751 may include bands 762 wrapped around braided structure 710 tocontrol the diameter of braided structure 710. Although two bands 762are shown in the exemplary embodiment of FIG. 14, other numbers of bands762 may be utilized, such as, for example, one, three, four, five, six,or a greater number of disks. Further, bands 762 may lack passages foractuation members 760, which extend past bands 762 between proximal end702 and distal end 704 of braided structure. Thus, as shown in theexemplary embodiment of FIG. 14, wrist 751 with braided structure 710may lack disks to fix the proximal 702 and distal 704 ends of braidedstructure 710 and/or disks to control the diameter of braided structure710.

According to an exemplary embodiment, braided structure 710 may extendalong a helical path between its proximal end 702 and distal end 704,such as in direction 706 or in direction 707. For example, theindividual filaments 714 may extend along helical paths. Providing apredetermined helical path for braided structure 710 may control thenumber of DOF's of braided structure 710 and thus control the motion ofbraided structure 710 and how braided structure 710 constrains themotion of wrist 700. For instance, controlling the helical pathtraversed by a braided structure 710 may affect the number of degrees offreedom permitted by braided structure 710 due to how individualfilaments are positioned relative to bending axes along the length ofthe braided structure 710.

According to an exemplary embodiment, braided structure 710 may extendalong a helical path having an angular extent of approximately 180degrees between proximal end 702 and distal end 704 to provide braidedstructure 710 with zero degrees of freedom. For instance, filaments 714may extend along a helical path having an angular extent ofapproximately 180 degrees between proximal end 702 and distal end 704.The 180 degree angular extent of the helical path results in a braidedstructure 710 in which the length of filaments 714 is not conserved whenthe braided structure 710 is moved. Because ends of the braidedstructure 710 are fixed and do not permit a change in length, bendingand translation motions are substantially prevented, which wouldotherwise result in a change in length of the braided structure 710. Abraided structure 710 with zero degrees of freedom would be resistant tobending like a wrist but may bend a limited degree due to deformation offilaments and/or plaits under load.

According to another exemplary embodiment, braided structure 710 mayextend along a helical path having an angular extent of approximately360 degrees between proximal end 702 and distal end 704 to providebraided structure 710 with two degrees of freedom, such as in arbitrarypitch and yaw directions. For example, filaments 714 may extend along ahelical path having an angular extent of approximately 360 degrees asthey traverse from the proximal end 702 and to the distal end 704. Byextending along a helical path having an angular extent of approximately360 degrees, braided structure 710 may function like a wrist comprisinga series of connected disks in an ABAB configuration with two degrees offreedom, because bending motions in pitch and yaw directions may bepermitting because the bending motions are length conservative.Conversely, translation motion, such as to move braided structure 710into an S-shape, would be substantially prevented because thetranslation motion would not be length conservative and the fixed endsof the braided structure 710 would substantially prevent a change inlength of braided structure 710. On the other hand, because braidedstructure 710 has only two degrees of freedom when extending along ahelical path having an angular extent of approximately 360 degrees,translation motion of braided structure 710 in X-Y space can beconstrained, so that braided structure 710 may articulate along an arc(e.g., like a wrist) but one portion of braided structure 710 may nottranslate laterally relative to another portion of braided structure 710(e.g., like a parallel motion mechanism, as described below in regard tothe exemplary embodiment of FIG. 17 and in U.S. Pat. No. 7,942,868,published May 17, 2011, and U.S. application Ser. No. 11/762,165, filedon Jun. 13, 2007, and published as U.S. Pub. No. US 2008/0065105). Alateral translation movement of one portion of braided structure 710relative to another portion of braided structure 710 may not be desiredfor a wrist including the braided structure 710.

According to another exemplary embodiment, braided structure 710 mayextend along a helical path having an angular extent of approximately720 degrees between proximal end 702 and distal end 704, so that themotion of braided structure 710 is substantially unconstrained. Forexample, filaments 714 may extend along a helical path having an angularextent of approximately 720 degrees as they traverse from the proximalend 702 to the distal end 704. A braided structure extending an angularextent of approximately 720 degrees would be similar to two consecutivebraided structures each extending along a helical path having an angularextent of approximately 360 degrees, providing an overall braidedstructure with 4 DOFs (which would appear to be substantiallyunconstrained to a user) and permitting both bending movement andtranslation movement. As a result, not only may braided structure 710bend in arbitrary pitch and yaw directions like a wrist, but braidedstructure 710 may move into a S-shape or like a parallel motionmechanism, as described below in regard to the exemplary embodiment ofFIG. 17, so that longitudinal axes through each of proximal end 702 anddistal end 704 may be offset from one another but still substantiallyparallel to one another.

When a braided structure 710 is used in an articulatable member 700,braided structure 710 may be used to replace a series of disks connectedat joints, as shown in the exemplary embodiment of FIG. 11. In otherwords, braided structure 710 itself may provide the structure and bodyof the articulatable member 700 from one end to another. In such anexemplary embodiment, the articulatable member 700 can be used as awrist and have the same diameters as wrist structures discussed in theexemplary embodiments above. Further, braided structure 710 may haveboth torsional and compressive stiffness and be placed under bothtension and compression.

Although braided structure 710 may be used to replace connected disksand to provide wrist with a constrained motion, as in the exemplaryembodiment of FIG. 11, a braided structure also may be used inconjunction with connected disks to provide an alternative articulatablemember (e.g., wrist) with constrained motion. In this case, the braidedstructure may replace constraint tendons, such as constraint tendons330, 332, 334, 336 of the exemplary embodiment of FIG. 3. Turning toFIG. 15, a side view is shown of an articulatable member 800 thatincludes connected disks 801-805 and a braided structure 810. Disks801-805 may be connected and configured in the same manner as theexemplary embodiment of FIG. 3 (i.e., in an ABAB configuration and shownin FIG. 15). To constrain motion of disks 801-805, such as to permitcontrolled bending along an arc a braided structure 810 may be providedabout the exterior of disks 801-805, as shown in the exemplaryembodiment of FIG. 14. Braided structure 810 may be configured accordingto the exemplary embodiment of FIG. 11 and include filaments 714 forminginterwoven plaits 712 to form an overall hollow cylindrical or tubularstructure around disks 801-805. A proximal end 812 and a distal end 814of braided structure 810 can be fixed relative to disks 801-805.According to an exemplary embodiment, proximal end 812 and distal end814 of braided structure 810 may be fixed to place braided structure 810under tension, with disks 801-805 bearing compressive loads. Further, byplacing braided structure 810 around an exterior of disks 801-805, aninternal diameter of braided structure 810 may be controlled by disks801-805 themselves, according to an exemplary embodiment.

As discussed in the exemplary embodiments of FIGS. 3-15, anarticulatable member with a constrained motion may be a wrist. However,an articulatable member with a constrained motion is not limited to awrist. According to an exemplary embodiment, an articulatable memberwith constrained motion may be a parallel motion mechanism, thefunctions of which are described, for example, in U.S. Pat. No.7,942,868, published May 17, 2011, and U.S. Pub. No. US 2008/0065105,published Mar. 13, 2008, which are incorporated herein by reference intheir entireties.

With reference to FIG. 16, a distal portion 900 of a surgical instrumentis shown that includes a parallel motion mechanism 910 connected to aninstrument shaft 906. The instrument may be a camera instrument or asurgical instrument with an end effector 908 according to the exemplaryembodiment of FIG. 2. According to an exemplary embodiment, instrumentdistal portion 900 may, for example, include a wrist 902, which may beconfigured according to any of the exemplary embodiments describedabove, although the instrument may lack a wrist 902.

As shown in the exemplary embodiment of FIG. 16, parallel motionmechanism 910 may include a straight shaft section 916 that separates aproximal joint mechanism 912 from a distal joint mechanism 914. Similarto the exemplary embodiments of U.S. Pat. No. 7,942,868, published May17, 2011, and U.S. Pub. No. US 2008/0065105, published Mar. 13, 2008,joint mechanisms 912 and 914 and the opposite ends of straight section916 are coupled together so as to operate in cooperation with eachother. According to an exemplary embodiment, proximal joint mechanism912 and distal joint mechanism 914 may include a plurality of connecteddisks, similar to a wrist. The disks may include, for example,mechanical stops (not shown) to limit the motion of joint mechanisms912, 914, such as in pitch and/or yaw directions.

FIG. 20 shows an end view of an exemplary embodiment for a disk 1100 ofa joint mechanism for a parallel motion mechanism. Disk 1100 may includea central aperture 1102, connection portions 1104, and a plurality ofapertures for actuation members. For example, disk 1100 may include aplurality of apertures 1110 for wrist drive tendons, a plurality ofapertures 1120 for parallel motion mechanism drive tendons, and aplurality of apertures 1130 for constraint tendons, which are discussedfurther below. As depicted in the exemplary embodiment of FIG. 20,apertures 1110, 1120, 1130 may be located at the same distance (e.g.,radius) with respect to a center of disk 1100 (e.g., center of centralaperture 1102), or apertures 1110, 1120, 1130 may be located atdiffering distances (e.g., radius) with respect to the center of disk1100.

FIG. 17 shows the exemplary embodiment of FIG. 16 with parallel motionmechanism 910 actuated. As shown in FIG. 16, parallel motion mechanism910 may control the relative orientations of a distal end portion 917 ofparallel motion mechanism 910 and a proximal end portion 915 of parallelmotion mechanism 910. As a result, a longitudinal axis 913 throughdistal end portion 917 of parallel motion mechanism 910 may besubstantially parallel to a longitudinal axis 911 passing throughproximal end 915 of parallel motion mechanism 910 (longitudinal axis 911may also be the longitudinal axis of instrument shaft 906, not shown inFIG. 16). Thus, a position of end effector 908, camera device (notshown), or other component at distal end 904 of instrument distalportion 900 may be changed in X-Y space but the orientation of endeffector 908 relative to longitudinal axis 911 may be maintained (beforeany motion due to wrist 902 is accounted for).

Unlike the motion of a wrist, which may be constrained to substantiallyfollow an arc, the motion of parallel motion mechanism 910 may beconstrained to translate parallel motion mechanism 910 in X-Y space, asshown in the exemplary embodiment of FIG. 16. The motion of parallelmotion mechanism 910 may be constrained so that motion along an arc isminimized or prevented because motion along an arc through proximaljoint 912 to distal joint 914 would not translate the distal end portion917 of parallel motion mechanism 910 in X-Y space while maintaining theorientation of distal end portion 917 relative to proximal end 915. As aresult, parallel motion mechanism 910 may be constrained in asubstantially opposite manner to that of the wrists of the exemplaryembodiments of FIGS. 3-15. That is, the wrists may be constrained topermit bending motion along an arc but minimize or prevent translationmotion in X-Y space, which could result in an S-shape or the like, whilea parallel motion mechanism may be constrained to permit translationmotion in X-Y space but minimize or prevent bending motion along an arc.

Turning to FIG. 18, the exemplary embodiment of FIG. 16 is shown withexternal surfaces of shaft 906 and straight section 916 of parallelmotion mechanism 910 removed to reveal internal components. As shown inthe exemplary embodiment of FIG. 18, straight section 916 may include acentral tube 918 extending between proximal joint mechanism 912 anddistal joint mechanism 914. Central tube 918 may be hollow, permittingcomponents of an instrument to pass through the interior of central tube918, such as to wrist 902 and/or end effector 908.

As shown in the exemplary embodiment of FIG. 18, wrist drive tendons 920may extend from shaft 906 and parallel motion mechanism 910 to wrist 902where wrist drive tendons 920 may be attached to a distal end of wrist902 or distal end 904 of instrument distal portion 900 to actuate wrist902, as discussed above with regard to the exemplary embodiment of FIG.3. Wrist drive tendons 920 may extend over an exterior surface ofcentral tube 918, as shown in the exemplary embodiment of FIG. 18.According to an exemplary embodiment, wrist drive tendons 920 may passthrough an annular space provided between central tube 918 and an outercasing 919 (shown in FIGS. 16 and 17) of straight section 916.

An instrument further includes one or more tendons to actuate parallelmotion mechanism 910. For example, parallel motion mechanism actuationmembers 930 may extend from shaft 906 through parallel motion mechanism910 and be fixed to distal end 914 of parallel motion mechanism 910 sothat parallel motion mechanism 910 may be actuated, such as by applyingforces to tendons 930. According to an exemplary embodiment, actuationmembers 930 may be pull/pull actuation members or push/pull actuationmembers. Some parallel motion mechanisms, due to limitations on theamount of interior space within a parallel motion mechanism, may usethree drive tendons to actuate the parallel motion mechanism. However,parallel motion mechanisms of the exemplary embodiments described hereinmay provide an increase amount of interior space due to theirconfigurations, permitting various numbers of drive tendons to be used.For example, four actuation members 930 may be used to actuate parallelmotion mechanism 910, with actuation members 930 arranged in pairs,e.g., connected to capstans, similar to the actuation members 364 of theexemplary embodiment of FIG. 4, which provides a robust construction andcontrol for actuating drive tendons and parallel motion mechanism 910.Actuation members 930 may extend over central tube 918. According to anexemplary embodiment, actuation members 930 may pass through an annularspace provided between central tube 918 and an outer casing 919 ofstraight section 916.

Parallel motion mechanism 910 may further include one or more constraintmembers fixed at opposite ends of parallel motion mechanism 910,according to an exemplary embodiment. For example, constraint tendons940 may extend from distal end 915 of parallel motion mechanism 910 toproximal end 917, with constraint tendons 940 being fixed at distal end915 and proximal end 917. Constraint tendons 940 may be fixed in placevia, for example, welding constraint tendons 940 to a component ofparallel motion mechanism 910, crimping constraint tendon 940 to anotherobject, or by other techniques familiar to one of ordinary skill in theart. In the exemplary embodiment of FIG. 18, distal ends of constrainttendons 940 are fixed to a disk of distal joint mechanism 914 and fixedto a disk of proximal joint mechanism 912. As shown in the exemplaryembodiment of FIG. 18, one end of constraint tendons 940 may be fixed bydistal crimps 941 at distal end 917 of parallel motion mechanism 910 andanother end of constraint tendons 940 may be fixed by proximal crimps943 at proximal end 915 of parallel motion mechanism 910. As shown inthe exemplary embodiment of FIG. 18, constraint tendons 940 may extendover an exterior surface of central tube 918. According to an exemplaryembodiment, constraint tendons 940 may pass through an annular spaceprovided between central tube 918 and an outer casing 919 (shown inFIGS. 16 and 17) of straight section 916.

Although the parallel motion mechanisms of the exemplary embodimentsdescribed herein have similar motions and functions to the embodimentsdescribed in U.S. Pat. No. 7,942,868, published May 17, 2011, and U.S.Pub. No. US 2008/0065105, published Mar. 13, 2008, the parallel motionmechanisms of the exemplary embodiments described herein have differentstructures, which advantageously provide more interior room for morecomponents, such as drive tendons and/or constraint tendons, as well assmooth, precise motion of the parallel motion mechanisms.

According to an exemplary embodiment, parallel motion mechanism 910 doesnot include the stiffening brackets 1670 described in U.S. Pat. No.7,942,868, resulting in more interior space within parallel motionmechanism 910. Although stiffening brackets 1670 described in U.S. Pat.No. 7,942,868 take up some interior space, the configuration of thestiffening brackets 1670 increased the tensile force applied to anactuating cable 1680 connected to a bracket 1670, with both constraintcables and actuating cables extending straight through the parallelmotion mechanism. To address this, actuation members 930 of parallelmotion mechanism 910 may extend along a helical path along at least aportion of parallel motion mechanism 910. This is further illustrated inthe exemplary embodiment of FIG. 19, which shows a central tube 1018 ofa parallel motion mechanism with wrist drive tendons 1020, constrainttendons 1040, and parallel motion mechanism drive tendons 1032, 1034,1036, 1038. As shown FIG. 19, wrist drive tendons 1020 and constrainttendons 1040 may be substantially straight, while parallel motionmechanism drive tendons 1032, 1034, 1036, 1038 extend in helical pathsabout central tube 1018. According to an exemplary embodiment, parallelmotion mechanism drive tendons 1032, 1034, 1036, 1038 may extend along ahelical path having an angular extent of approximately 180 degrees alongcentral tube 1018, as shown in FIG. 19. For instance, parallel motionmechanism tendons 930 in FIG. 18, including parallel motion mechanismdrive tendon 934, may extend along a helical path having an angularextent of approximately 180 degrees from proximal end 915 of parallelmotion mechanism 910 to distal end 917 of parallel motion mechanism 910.

Because parallel motion mechanism actuating members may extend along ahelical path along at least a portion of a parallel motion mechanism, amechanical advantage may be provided to the tendons without the use ofstiffening brackets and mechanisms employed in other parallel motionmechanism designs. For example, when parallel motion mechanism 910 isactuated as shown in FIG. 17, parallel motion mechanism drive tendon 934is on the bottom side 950 of parallel motion mechanism 910 at proximalend 915, causing a positive change in length of drive tendon 934 andadditional tension to be exerted upon drive tendon 934. However, becausethe same drive tendon 934 extends along a helical path having an angularextent of approximately 180 degrees, drive tendon 934 is on the top side954 of parallel motion mechanism 910 at distal end 917, causing drivetendon 934 to experience a positive change in length at distal end 917as well, which also exerts tension upon drive tendon 934. Therefore,actuation members 930, including tendon 934, may extend along a helicalpath along parallel motion mechanism 910 to provide a mechanicaladvantage for actuating parallel motion mechanism 910, while alsoresulting in more interior space for components by eliminating otherinterior structural support elements.

In contrast to actuation members 930, constraint tendons 940 follow asubstantially straight path as they extend through parallel motionmechanism 910, as shown in the exemplary embodiment of FIG. 18. As aresult, when parallel motion mechanism 910 is actuated as shown in FIG.17, constraint tendons 940 on the bottom side 950 of proximal jointmechanism 912 experience a positive change in length. Because constrainttendons 940 are fixed at opposite ends of parallel motion mechanism 910,the same constraint tendons 940 running straight along the bottom sideof parallel motion mechanism 910 experience a negative change in lengthon bottom side 952 of distal joint mechanism 914, causing distal jointmechanism 914 and proximal joint mechanism 912 to bend in oppositemanners to provide the offset but parallel positioning of distal end 917and proximal end 915 of parallel motion mechanism 910.

As described in the exemplary embodiments of FIGS. 16-20, a parallelmotion mechanism may use tendons as mechanisms to constrain motion ofthe parallel motion mechanism. In other exemplary embodiments, aparallel motion mechanism may include a braided structure, as describedin the exemplary embodiments of FIGS. 11-15. According to an exemplaryembodiment, a braided structure may replace the disks in proximal jointmechanism 912 and distal joint mechanism 914 of parallel motionmechanism 910, in a manner as described in regard to the exemplaryembodiment of FIG. 11. In another exemplary embodiment, a braidedstructure may be placed around the disks of proximal joint mechanism 912and distal joint mechanism 914, as described in regard to the exemplaryembodiment of FIG. 15.

Although wrists and parallel motion mechanisms according to theexemplary embodiments described herein may be used separately (i.e., aninstrument may include a wrist or a parallel motion mechanism), aninstrument may include both a wrist and a parallel motion mechanism.When an instrument includes both a wrist and a parallel motionmechanism, the wrist may include constraint mechanism, such asconstraint tendons, separate from constraint mechanisms, such asconstraint tendons, of the parallel motion mechanism. For example, thewrist includes a first constraint mechanism, such as a first set of oneor more constraint tendons, and the parallel motion mechanism includes asecond constraint mechanism, such as a second set of one or moreconstraint tendons. According to an exemplary embodiment, when the wristand parallel motion mechanism have separate constraint tendons, theconstraint tendons of the wrist and parallel motion mechanism maydiffer, such as by having differing diameters, or other structural ormaterial differences, which may be chosen to achieve desired motioneffects, for example.

According to another embodiment, the wrist and parallel motion mechanismuse the same constraint mechanism, such as the same constraint tendons.Using the same constraint mechanism in the wrist and parallel motionmechanism may be efficient for conserving the interior space of aninstrument to use the same constraint mechanisms for both a wrist and aparallel motion mechanism.

With reference to FIG. 21, a partial view is shown of a distal endportion 1200 of an instrument that includes a wrist 1202 and a parallelmotion mechanism 1204, which may be configured according to theexemplary embodiments of FIGS. 16-20. Wrist 1202 may be configuredaccording to the exemplary embodiments of FIGS. 3-14 and parallel motionmechanism 1204 may be configured according to the exemplary embodimentsof FIGS. 15-19. As shown in FIG. 21, wrist 1202 may be located distallyto parallel motion mechanism 1204. Wrist drive tendons 1220 may extendthrough parallel motion mechanism 1204 to wrist 1202 and through wrist1202 to a distal end of wrist 1202 or distal end 1203 of instrumentwhere wrist drive tendons 1220 are fixed to actuate wrist 1202. Parallelmotion mechanism drive tendons 1230 extend through parallel motionmechanism 1204 and may be fixed at a distal end of parallel motionmechanism 1204.

According to an exemplary embodiment, wrist 1202 and parallel motionmechanism 1204 share constraint tendons that constrain motion of bothwrist 1202 and parallel motion mechanism 1204. For example, constrainttendons for both wrist 1202 and parallel motion mechanism 1204 include afirst portion of constraint tendons 1240A that extend through parallelmotion mechanism 1204, are fixed (such as, for example, at a distal endof parallel motion mechanism 1204, at proximal end of wrist 1202, orbetween parallel motion mechanism 1204 and wrist 1202, such as viacrimps 1210 discussed below) have a second portion of constraint tendons1240B that extend through wrist 1202, and are fixed again. The first andsecond portions 1240A, 1240B are of the same, continuous constrainttendons, so that the same constraint tendons (portions 1240A, 1240B) maybe used to constrain both wrist 1202 and parallel motion mechanism 1204.For instance, the constraint tendons may be fixed at a distal end ofparallel motion mechanism 1204, a proximal end of wrist 1202, or in aconnection region 1205 between wrist 1202 and parallel motion mechanism1204, as shown in the exemplary embodiment of FIG. 21. Thus, one set ofconstraint tendons (including portions 1240A, 1240B) may be used toconstrain the motion of both wrist 1202 and parallel motion mechanism1204, which provides an efficient use of interior space of aninstrument.

According to an exemplary embodiment, wrist 1202 and parallel motionmechanism 1204 have separate constraint tendons that respectivelyconstrain motion of wrist 1202 and parallel motion mechanism 1204. Forexample, first portion of constraint tendons 1240A represents a firstset of one or more constraint tendons and second portion of constrainttendons 1240B represents a second set of one or more constraint tendonsseparate from the first portion of constraint tendons 1240A. When wrist1202 and parallel motion mechanism 1204 have different constrainttendons, the constraint tendons for parallel motion mechanism 1204(e.g., first portion 1240A) may be fixed, for example, at a distal endof parallel motion mechanism 1204, at proximal end of wrist 1202, orbetween parallel motion mechanism 1204 and wrist 1202, and theconstraint tendons for wrist 1202 (e.g., second portion 1240B) may befixed at, for example, at a distal end of parallel motion mechanism1204, at proximal end of wrist 1202, or between parallel motionmechanism 1204 and wrist 1202, extend through wrist 1202, and be fixedat a distal end of wrist 1202.

The constraint tendons may be fixed, according to the exemplaryembodiments of FIGS. 3-20. For instance, the first portion of constrainttendons 1240A may extend through parallel motion mechanism 1204, throughcrimps 1210 that fix constraint tendons 1240 relative to instrumentdistal portion 1200, and end at crimps, with the second portion ofconstraint tendons 1240B separately extending through wrist 1202 (suchas when separate tendons constrain wrist 1202 and parallel motionmechanism 1204), or the constraint tendons may continue from crimps 120through wrist 1202 as a second portion 1240B of the same constrainttendons that extend through both parallel motion mechanism 1204 andwrist 1202. Further, the constraint tendons may be arranged according tothe exemplary embodiments of FIGS. 3-20, with, for example, theconstraint tendons (e.g., portions 1240A, 1240B) extending in asubstantially straight direction through parallel motion mechanism 1204and extending along a helical path through at least a portion of wrist1202.

The exemplary embodiments and methods described herein have beendescribed as being utilized with surgical instruments for teleoperatedsurgical systems. However, the exemplary embodiments and methodsdescribed herein may be used with other surgical devices, such aslaparoscopic instruments and other manual (e.g., hand held) instruments,and non-surgical devices, such as devices that include any of a varietyof actuated articulatable members, including but not limited to wristsand/or parallel motion mechanisms, whether the devices are teleoperated,remote controlled, or manually operated.

By providing surgical instruments with constraint mechanisms accordingto the exemplary embodiments described herein, articulatable members areprovided that have simpler force transmission mechanisms that are easierto control and less costly to manufacture, while the articulatablemembers provide substantially repeatable, smooth, precise motions.

Further modifications and alternative embodiments will be apparent tothose of ordinary skill in the art in view of the disclosure herein. Forexample, the systems and the methods may include additional componentsor steps that were omitted from the diagrams and description for clarityof operation. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the present teachings. It isto be understood that the various embodiments shown and described hereinare to be taken as exemplary. Elements and materials, and arrangementsof those elements and materials, may be substituted for thoseillustrated and described herein, parts and processes may be reversed,and certain features of the present teachings may be utilizedindependently, all as would be apparent to one skilled in the art afterhaving the benefit of the description herein. Changes may be made in theelements described herein without departing from the spirit and scope ofthe present teachings and following claims.

It is to be understood that the particular examples and embodiments setforth herein are non-limiting, and modifications to structure,dimensions, materials, and methodologies may be made without departingfrom the scope of the present teachings.

Other embodiments in accordance with the present disclosure will beapparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein. It isintended that the specification and examples be considered as exemplaryonly, with a true scope and spirit being indicated by the followingclaims.

What is claimed is:
 1. An articulatable member, comprising: a plurality of links extending in a series from a proximal end link to a distal end link, adjacent links of the plurality of links being pivotably coupled to form joints between adjacent links; an actuation member extending from the proximal end link to the distal end link, wherein the actuation member is operably coupled to the plurality of links to transmit force to bend the articulatable member from a neutral position; and a constraint member extending from the proximal end link to the distal end link, wherein the constraint member has opposite ends that are fixed to the distal end link and the proximal end link, respectively, wherein the constraint member extends through a throughhole in each link of the plurality of links, the throughhole being radially offset from a central axis of the link, and wherein the constraint member follows a helical path along at least a portion of the articulatable member from the proximal end link to the distal end link; wherein, in a straight configuration of the articulatable member, the constraint member is under tensile force between the opposite ends.
 2. The articulatable member of claim 1, wherein the articulatable member is a wrist.
 3. The articulatable member of claim 1, wherein the constraint member is arranged to passively constrain translation motion of the plurality of links.
 4. The articulatable member of claim 1, wherein the actuation member extends substantially straight along the articulatable member from the distal end link to the proximal end link.
 5. The articulatable member of claim 1, wherein rotational axes of consecutive joints of the joints between adjacent links are oriented orthogonally to each other.
 6. The articulatable member of claim 5, wherein an angular extent of the helical path of the constraint member between adjacent links of the plurality of links is about 90 degrees.
 7. The articulatable member of claim 5, wherein the constraint member comprises a plurality of constraint members, wherein a helical path of a first constraint member of the plurality of constraint members is right-handed, and wherein a helical path of a second constraint member of the plurality of constraint members is left-handed.
 8. The articulatable member of claim 1, wherein the joints between adjacent links comprise two consecutive joints and two flanking joints, a first of the two flanking joints flanking a first of the two consecutive joints, and a second of the two flanking joints flanking a second of the two consecutive joints, wherein each of the two consecutive joints has a rotational axis that extends in substantially a same direction, and wherein each of the flanking joints has a rotational axis that extends in a direction substantially orthogonal to the direction of the rotational axes of the two consecutive joints.
 9. The articulatable member of claim 8, wherein an angular extent of the helical path of the constraint member between the two consecutive joints is about 180 degrees.
 10. The articulatable member of claim 1, wherein the constraint member is part of a braided structure.
 11. The articulatable member of claim 10, wherein an angular extent of the braided structure between a distal end and a proximal end of the braided structure is about 180 degrees.
 12. The articulatable member of claim 10, wherein an angular extent of the braided structure between a distal end and a proximal end of the braided structure is about 360 degrees.
 13. The articulatable member of claim 10, wherein an angular extent of the braided structure between a distal end and a proximal end of the braided structure is about 720 degrees.
 14. The articulatable member of claim 10, further comprising a member disposed internal to the braided structure and a member disposed external to the braided structure to limit expansion and contraction of the braided structure.
 15. The articulatable member of claim 10, wherein the braided structure forms a body structure of the articulatable member from the proximal end link to the distal end link.
 16. The articulatable member of claim 10, wherein the braided structure constrains motion of the plurality of links.
 17. The articulatable member of claim 1, wherein the articulatable member is a wrist of a surgical instrument.
 18. The articulatable member of claim 1, further comprising: a plurality of actuation members, wherein the actuation member is one of the plurality of actuation members; and a plurality of constraint members, wherein the constraint member is one of the plurality of constraint members.
 19. The articulatable member of claim 1, wherein the plurality of links further comprises at least one intermediate link between the proximal end link and the distal end link.
 20. A surgical instrument, comprising: a shaft; a force transmission mechanism connected to a proximal end of the shaft; a parallel motion mechanism connected to a distal end of the shaft; a wrist comprising a plurality of links, the wrist being coupled to a distal end of the parallel motion mechanism; an actuation member operably coupled to transmit force from the force transmission mechanism to bend the wrist from a neutral position; and a constraint member extending through the wrist and the parallel motion mechanism, the constraint member arranged to passively constrain motion of the wrist and the parallel motion mechanism; wherein opposite ends of the constraint member are respectively fixed to a distal end of the wrist and a proximal end of the parallel motion mechanism; wherein a portion of the constraint member between the opposite ends is fixed to a portion of the surgical instrument between the wrist and the parallel motion mechanism; and wherein the constraint member follows a substantially straight path along the parallel motion mechanism and a helical path along at least a portion of the wrist.
 21. The surgical instrument of claim 20, further comprising an end effector coupled to a distal end of the wrist.
 22. The surgical instrument of claim 20, wherein the actuation member is operably coupled to the force transmission mechanism and the wrist so as to transmit the force from the force transmission mechanism to bend the wrist, and wherein the actuation member extends in a substantially straight path along the parallel motion mechanism and the wrist.
 23. The surgical instrument of claim 20, wherein the actuation member is operably coupled to the force transmission mechanism and the parallel motion mechanism to transmit the force from the force transmission mechanism to bend the parallel motion mechanism, and wherein the actuation member follows a helical path along at least a portion of the parallel motion mechanism. 